Horizon Zero Dawn

• Do the hunting lodge quests, they are a pile of XP.

• Always keep at least one of every item to trade for gear

• Make sure you clear the sidequests in the first area, one give you an upgrade to your spear that you can't get any other way.

• Drawing back a shot is for accuracy, not damage. Feel free to shoot wildly if you are close enough.
• While you always want the highest tier equipment you can get your hands on, the game does expect you to have a large variety of types of equipment and change out as the situation demands.
• Always kill and harvest normal wildlife you come across, a few of the higher tier weapons and all the mid to high tier carry capacity upgrades require animal bones and skins. Their drop rate isn't too great.
• Also you can craft meat into health potions.
• Harvest arrows are incredibly useful for ammo crafting resources; for example if you were to shoot off a blaze canister with a harvest arrow you'd get 6 blaze from it instead of 1.
• All the collectibles have more details if you look at them in the notebook after you've picked them up.