How goes it everyone. Just started playing today, I've played lots of other hunting games (Toukiden, God Eater, Soul Sacrifice etc) but the only Monster Hunter title I've ever played was the PS2 game because I couldn't deal with the controls on handheld and I didn't own a Wii-U.
So far I'm a big fan it but I'm having a tough time figuring out which weapons suit me the most. I think so far I'm leaning towards either Lance or Gunlance but on GL I'm having a bit tougher a time figuring out the right times to use shells, Wyrmfire and the wyrmstake. I think I lean a bit more into Gunlance then than I do Lance but it seems like Gunlance has to be sharpened way more then many of the other weapons.
I like the hammer also but I wish the hammers were a little bit larger then they are in terms of length.
I am maining gunlance for this game and love it. The strongest playstyle that I am aware of with it is the full burst infinite combo, where you start with an upswing, do a down slam, full burst, wide swing and then quick reload, following the quick reload you can go direct into the down slam and repeat infinitely. The down slam and wide swing will hit without bouncing off tough spots (e.g horns) and the shelling does fixed damage, ignoring armour. Shelling does eat through sharpness quickly, so speed sharpening or trying to always get the sharpening food skill will help, though I've always prioritised other skills over sharpening.
You want to start aiming to get some artillery gear because it will increase damage of shells, so Anjanath legs and Paolomu gloves will get you to level 2 and that might be as much as you can get in low rank, once you reach high rank you will want to get capacity boost too, I dont recall if it is in low rank.
Best gunlance for full burst is the max Rathian tree, however up until then I'd argue that the Great Jagras tree is spectacular and criminally overlooked. It is very easy to make and it's second last version has very high base damage (comparable to a number of max gunlances) and allows for the strongest full burst oriented gunlance you can get before defeating elder dragons.
Wyrmstake I almost never use because it ends a combo and is very slow, particularly if you whiff. Wyvern Fire is very situational, I don't often use it in the middle of a fight because it is slow, but if the monster is sleeping I might use it with some barrel bombs to do some nice damage waking it up.
With all that being said do not forget to use your shield, it blocks almost all attacks and you can do a poke from it which is weak but shouldn't be overlooked as it allows you to reach heads pretty easily and fairly safely.