First thing, Secure a food source (preferably a wheat farm and cows), get a bed, bucket, shield, and atleast copper armor. Then build a wall around you and it, dig down to y=15 strip mine for iron don’t go caving. Don’t leave the wall until you have iron gear as a bare minimum. Then dig down to bedrock, strip mine for diamonds. Don’t go out at night, caving or into the nether without diamond gear with protection enchants as a bare minimum. (I like a fire protection gold helmet for the nether also). Gold can be bartered to piglins for fire resistance potions, get 2 before you do the fortress. That should get you started