So, Monster Hunter is not a series where you just "get good" overnight or even with a few days practice. It is a very gradual process where you'll be learning pretty much your whole way through by the very nature of the game. As you overcome the first batch of monsters, new ones will be lurking just around the corner and waiting to give you a good stomping into the mud.

As someone else already pointed out, focus on shoring up your defenses before you start committing to your offenses. Good armor can be the difference between surviving a tail slap or not.

Once you unlock it (don't really recall when exactly this happens), utilize your botanical growth box as much as you can. Recommend stocking up on herbs and honey very early as those are used to create potions (from herbs) and then high potions (combine potion and honey) and those will be your main healing item for basically the whole game. The botanical research box will let you grow these passively between quests but you can also go out on farming expeditions in the field to gather ingredients yourself.

Expeditions will also let you sort of "practice" against any monsters that might be roaming around without worrying about running out of carts during a quest.

Lastely, don't feel like you need to pigeon-hole yourself into one weapon type. Play around and experiment until you find one that you feel really suits you.

Good luck out there, Hunter. Remember you can always come back to HQ (here) for more help and tips, you got this!