First Rebuild

The thought that should be first and foremost in your mind is that there is no such thing as being too clean; you can make 100 other mistakes, but parts not being clean does not have to be one of them.
Another thought is that assembling an engine is just another jig-saw puzzle, the pieces are just bigger and heavier, pay attention to how they fit together; if something doesn't "feel" right, it probably isn't, back up and find out what is wrong.

Good luck and have fun.