Preparing for a mission in Monster Hunter is sort of like packing for a vacation. There's a lot to think about, and you don't want to be out the door just as you realize you left an essential item behind.
For Monster Hunter veterans, knowing which items are essential should be second nature by now. But if you're new to the series, being confronted with dozens upon dozens of potentially useful things can be pretty intimidating. For those of you still coming to terms with Monster Hunter's demands, read on for a list of which things you should bring along, and why said things are important.
By far, a finely-cooked chunk of meat will be one of your greatest assets in Monster Hunter. Every one of your actions requires stamina, and while this meter always recharges, over the course of a mission, its maximum will slowly drop. Well-Done Steak is simply the best of all Monster Hunter meats, and you can even make it yourself: Just use the BBQ Spit while you have some Raw Meat in your inventory, and your character will begin grilling it to perfection. It's your responsibility to pull it out of the fire in time, though, so be sure to hit the button when the meat has reached its second of three levels of browness—it's a somewhat short window of time. (The short ditty that plays during the cooking animation can also help you figure out the timing.) If you let it cook too long, you'll get a Burnt Steak, which actually reduces your maximum stamina, so make sure you toss it from your inventory.
Even if you're out in the wild just for the sake of gathering supplies, you might spot a few random foes that would add some much-needed items to your stock. But as you use your weapon throughout a mission, it'll grow duller over time—the sword icon in the UI should let you know your weapon's current state. Luckily, it only takes a single Whetstone to bring your current weapon back to its maximum sharpness. They're pretty cheap to buy back at the village, but if you're looking to refill your stock for free, they often turn up at Gathering Points involving mining.
Potions are the most dependable HP-restorer in Monster Hunter, so you'll want to make sure you're fully stocked at all times. Like the Whetstone, these can be purchased pretty cheaply back at the village, but you can also make them with two items found pretty regularly at Gathering Points: Herbs and Blue Mushrooms. When combined, one of each will net you a single Potion. And if you combine a Potion with Honey, you'll get a Mega Potion, which restores a lot more HP. If you're rolling against a particularly difficult monster and know that specific map offers a beehive or two, consider bringing some standard Potions along with the Mega ones. Then, you can combine them with Honey should you need to replenish your stock of Mega Potions.
If You're Fighting Monsters
While they're not 100% essential, using Nutrients can give you the edge you need against particularly tough monsters. In essence, Nutrients are basically Well-Done Steaks, but for your HP: Gulping one down will provide a temporary boost to your maximum health. Since the effects are temporary, it's suggested you don't down any Nutrients until you actually find and start fighting the monster in question. You can make Nutrients by combining a Blue Mushroom with a Godbug, and, as with Potions, you can combine basic Nutrients with Honey to make more effective Mega Nutrients.
While Monster Hunter starts off by pitting you against one Monster per map, it won't be long until you're tangling with two, and have to scare one away for the sake of concentrating on the other. Or, it could be the case that a monster is simply too much for you to handle, and you need to get away in order to rethink your strategy. For these occasions, Dung Bombs come in handy. Even if you're fighting brutal, lizard-brained beasts, they still have some sense of decorum, and will flee if hit with what amounts to a poop explosion. You can make these by combining a Bomb Casing (Sap Plant + Stone) with Dung, which can be found in the appropriate piles, and is often a reward for killing certain monsters.
Monster Hunter monsters have a survival instinct, and will flee once they've taken enough damage in order to eat or sleep to regain some of their lost HP. To keep track of them as they scurry about the map, be sure to chuck a Paintball (Sap Plant + Paintberry) in their direction not long after you first encounter them. If you land a hit, a pink dot will appear on the map, indicating the monster's current location. As with most items in Monster Hunter, the effects are temporary, so be sure to toss another Paintball if the dot is on the verge of disappearing, or has disappeared completely.
Traps and Tranquilizers
In order to get the most parts from a monster, you'll have to trap it instead of killing it—which is easier said than done. In order to successfully trap a monster, you'll have to wait until it's on its last legs—indicated by specific animations and behaviors—then lure the monster into a trap where it can easily be pelted with tranquilizers. To make one of the two kinds of traps, you'll need to combine a Trap Tool with either a Net (which gets you a Pitfall Trap) or a Thunderbug (which gets you a shock trap). And to make Tranq Bombs, you'll need to combine a Tranquilizer with a Bomb Casing (Sap Plant + Stone). You should probably fill your inventory with the max amount, since it often takes a few tries to successfully trap a monster.
Beyond the Basics
Of course, this collection of items is just enough to get you started. As your adventures in Monster Hunter continue, you'll also need to bring along items to account for the status effects inflicted by certain monsters, as well as the environment itself. But, at the very least, the essential items above should help you through the initial learning curve. Happy hunting!