To start you're going to want to loot the gas station you start at. There is plenty of food and lots of shulker boxes here. Shulker boxes are going to be some of your best storage available. Dump out the trash that you don't want just on the ground, it'll despawn on its own.
After you've looted the gas station, making sure to search the entire area to get all the loot that's available, look to your nearby surroundings. There are a number of styles of cities, towns, and villages in this pack. Most villages are going to have similar function to typical villages, except the villagers will be more lively and interactable. You can try chatting with them in the regular chat window and they'll respond! You're going to want to make a mixed zoning city your first goal; it will have guns and plenty of loot. These are distinguished by their visible stop lights and mixed zoning with residental and business districts being mixed together. There are also abandonded stretches of corporate offices, these typically have sparse loot, but have chances of having valuable diamonds and other materials. You can find still populated cities as well, these are modeled after various styles of soviet urban areas. Finally you can find suburban neighborhoods with familiar gas stations and police stations. These have decent loot, and plenty of shulker boxes.
Once you find a gun you can reload with "F" it if you have the proper ammo in your inventory. You're going to wind up with many calibers, it's recommended to keep 1 shulker box per caliber. After you've gathered enough materials, you're going to want to build an airship. These are craftable in the crafting table and will need coal or charcoal for fuel.
Once you've built an airship and have decent weapons and armor, proceed to the nether and ender dragon fight. Afterwards you can fly your airship to the outer islands and continue your explorations.