I have several sets of unidentified Lego bags with no part number. How can I figure out what to build?
You must classify parts first and find out which parts you have. You can always use Rebrickable website which is a great system that gives you the sets you can build with your parts. Most difficult part of the answer is of course classifying the parts and upload them to your Rebrickable account but once you done you can find out what you have and google the instructions.