Summarize the following:
You'll need a place to stay while you work on your house. When you build your house, be sure to use cobblestone (not wood) so that it will be ghast-proof. Make sure you have an iron door with a lever or button inside and out. Don't bother placing a bed, because if you try to sleep in it, it will explode. You may need to clear out the pigmen and blazes - just remember that all of the pigmen will attack you if you injure just one - and make sure to destroy all blaze spawners (with a pickaxe). The Nether Fortress does make a quite decent house; there are hiding places inside mountains and rooms deep inside where you can hide from ghasts and stuff. They are very decent places to live and contain plenty of bricks and staircases, blazes for blaze rods for potion making, treasure chests, and a Nether-wart farm. What else could a Minecrafter ask for? You can get rotten flesh from zombie pigmen (climb a tower before fighting them, because they will swarm at you). Rotten flesh may give you the hunger effect, but you can drink milk (if you were able to get a cow through the portal) or bring a milk bucket before entering the nether. You can also drink a potion to stop the effect. If you bring bowls, you can make mushroom stew in your inventory crafting grid from the mushrooms found in the Nether. There are no other food sources in the Nether unless you brought trees or seeds with you. If you bring trees or seeds, you should also bring dirt. Yes, it's a no-brainer because the materials needed are mostly in the Nether to make this, and so are the ingredients: blaze rods, ghast tears, etc. You can also make splash potions for pesky pigmen packs that you have started a fight with. Either way, it's essential unless you want to easily die after eating rotten flesh.
Dig into a mountain. If you can, find a Nether fortress. Only eat rotten flesh if you have nothing else. Make a brewing stand.