Oh wow cool Ceric. Few tips to start off with. Read what the NPC are telling you. In the text they tend to have tips as well as story so it is is good to pay attention to them. Getting full armor sets is helpful since if you have the full set you have all the skills that the armor provides. Armor skills need to have 10, 15, or 20 points to activate. Most skills use 10 points though. Save everything you get and put it in your box after quests. Something may not seem like much but it could be used to make armor,weapons, or items.
Finally a few sites that are helpful. The Monster Hunter Tri wiki.Just put that into google and it should be the first result.
http://divinewh.im/ This is a good site to make bowgun sets without actually making the guns. So you can see before hand what the bowgun fires. Also good for making armor sets later on in the game. Mixed armor sets can make some good skills but generally when you are starting it is best to have all the pieces of a specific armor.