First thing you need is ground beef with fat in it! Lean ground beef leads to dry, tasteless burgers - in my opinion 
In the Disco near us, they sell two different grades of ground beef and I always buy the lighter-colored, cheaper ones because there's more fat (and yeah, who knows what else).
For each burger, I used to weigh them, about 140 grams is a good size, but I have gotten to the point where I can grab a big fistfull of meat and hit the size just right. Form the patties into a ball, making sure you get the air spaces out - but don't compact it too much so you don't get a real dense burger. When you flatten it out to make the patty, make sure you have the meat on something that can spin so you can make it nice and round and flat (one hand flat on top pressing down, other hand on edge, running along the edge of the patty to form and spinning the patty as you go to make it round). When you've formed the patty, take two or three fingers and press down right in the middle, about halfway through the patty - this keeps the patty from swelling up in the middle with larger quantities of meat as it cooks.
Don't overcook. Better a little rare than cooked like a hockey puck (I've never been sick from rare hamburgers, though here I tend more towards medium than rare, to be sure). Get a meat thermometer if you're unsure and remove the patty when the center's around 130-135 degrees farenheit (remember that meat continues to cook a little once you take it off the heat source).
I usually just put seasoning on both sides of my patties instead of mixing it into the meat before forming patties. If you mix seasonings into the meat, use more than you think you need because the flavor just doesn't come through. For me, seasoned salt from the States makes the best tasting burgers (I bring bottles of it back every time I go, as well as some other blends - one day I may be forced to make my own seasoning blends!). Salt, pepper and garlic powder can do pretty good.
If you like a smoky taste, mix some liquid smoke with the meat before you make the patties. You have to use more than you would think with that, as well. The liquid smoke they sometimes have in the supermarkets here can be extraordinarily expensive, a little tiny bottle for somewhere near 100 pesos I think. I bought a liter bottle in barrio China more than a year ago for about 80 pesos (obviously more expensive now!) and I'm down to about a quarter of the bottle - going to have to go find some more soon.
Whatever you do, don't put bread crumbs or anything like that in the meat. We're not making meat loaf here. (I don't even like onions and other stuff mixed in, but that's just flavor - you get that with raw or sauteed onions as a topping) I've heard that's supposed to make them juicier, but anytime I've tried it, it completely ruins the consistency of the meat and hasn't helped me with juiciness (but then, I like my burgers pink in the middle anyway, and with fatty meat that almost guarantees a juicy burger!). When you cook the patty, cook it relatively slow - about a quarter to a third of the "flame dial" measured from its lowest setting is what I use. Cook them on one of those cast-iron grilling thingies - make sure it's good and hot before you put the patty on.
Other than that, burgers are pretty simple, just play around with your seasonings to see what you like.
Something else that's really good with ground beef, BTW - stuffed hamburger patties. Not meant to be eaten as a hamburger/sandwich, but rather as an entree. Take two very thin (quarter of an inch or so maybe, working from memory here) patties, pressed out larger than a normal hamburger patty. Maybe create the patties on wax paper so they're easy to pick up after being pressed. You may want to place the patties in the fridge to get them cold again for the forming process (depends on how many you're making and how long it takes to make them). Place (a lot of) grated cheese, sauteed onions (or chopped, raw) and chopped jalepenos in a mound on top of one patty (keep the filling away from the edges of the patty), cover with the other patty, press the patties together tightly at the edges (not an easy task and takes some practice!). The two patties have to be well sealed or the cheese escapes while cooking. After I've pressed the patties together, I pick the whole thing up and form/press some more to make it a regular-looking patty (though much bigger than a hamburger patty). Season the outside of the patties. I usually broil these (slowly) in the oven, although you could cook them slowly in a pan, covered. I also have a tool that makes the creation and filling process easier, but I used to do it completely by hand as described. Yummy, yummy delicious.
In the Disco near us, they sell two different grades of ground beef and I always buy the lighter-colored, cheaper ones because there's more fat (and yeah, who knows what else).For each burger, I used to weigh them, about 140 grams is a good size, but I have gotten to the point where I can grab a big fistfull of meat and hit the size just right. Form the patties into a ball, making sure you get the air spaces out - but don't compact it too much so you don't get a real dense burger. When you flatten it out to make the patty, make sure you have the meat on something that can spin so you can make it nice and round and flat (one hand flat on top pressing down, other hand on edge, running along the edge of the patty to form and spinning the patty as you go to make it round). When you've formed the patty, take two or three fingers and press down right in the middle, about halfway through the patty - this keeps the patty from swelling up in the middle with larger quantities of meat as it cooks.
Don't overcook. Better a little rare than cooked like a hockey puck (I've never been sick from rare hamburgers, though here I tend more towards medium than rare, to be sure). Get a meat thermometer if you're unsure and remove the patty when the center's around 130-135 degrees farenheit (remember that meat continues to cook a little once you take it off the heat source).
I usually just put seasoning on both sides of my patties instead of mixing it into the meat before forming patties. If you mix seasonings into the meat, use more than you think you need because the flavor just doesn't come through. For me, seasoned salt from the States makes the best tasting burgers (I bring bottles of it back every time I go, as well as some other blends - one day I may be forced to make my own seasoning blends!). Salt, pepper and garlic powder can do pretty good.
If you like a smoky taste, mix some liquid smoke with the meat before you make the patties. You have to use more than you would think with that, as well. The liquid smoke they sometimes have in the supermarkets here can be extraordinarily expensive, a little tiny bottle for somewhere near 100 pesos I think. I bought a liter bottle in barrio China more than a year ago for about 80 pesos (obviously more expensive now!) and I'm down to about a quarter of the bottle - going to have to go find some more soon.
Whatever you do, don't put bread crumbs or anything like that in the meat. We're not making meat loaf here. (I don't even like onions and other stuff mixed in, but that's just flavor - you get that with raw or sauteed onions as a topping) I've heard that's supposed to make them juicier, but anytime I've tried it, it completely ruins the consistency of the meat and hasn't helped me with juiciness (but then, I like my burgers pink in the middle anyway, and with fatty meat that almost guarantees a juicy burger!). When you cook the patty, cook it relatively slow - about a quarter to a third of the "flame dial" measured from its lowest setting is what I use. Cook them on one of those cast-iron grilling thingies - make sure it's good and hot before you put the patty on.
Other than that, burgers are pretty simple, just play around with your seasonings to see what you like.
Something else that's really good with ground beef, BTW - stuffed hamburger patties. Not meant to be eaten as a hamburger/sandwich, but rather as an entree. Take two very thin (quarter of an inch or so maybe, working from memory here) patties, pressed out larger than a normal hamburger patty. Maybe create the patties on wax paper so they're easy to pick up after being pressed. You may want to place the patties in the fridge to get them cold again for the forming process (depends on how many you're making and how long it takes to make them). Place (a lot of) grated cheese, sauteed onions (or chopped, raw) and chopped jalepenos in a mound on top of one patty (keep the filling away from the edges of the patty), cover with the other patty, press the patties together tightly at the edges (not an easy task and takes some practice!). The two patties have to be well sealed or the cheese escapes while cooking. After I've pressed the patties together, I pick the whole thing up and form/press some more to make it a regular-looking patty (though much bigger than a hamburger patty). Season the outside of the patties. I usually broil these (slowly) in the oven, although you could cook them slowly in a pan, covered. I also have a tool that makes the creation and filling process easier, but I used to do it completely by hand as described. Yummy, yummy delicious.
