You do want to use horizontal and not vertical dropouts when making your first frame. No competent advice would suggest it is better to start with verticals because it is much more difficult to get the chainstays to be exactly the same length so a wheel centers. That is one of the most challenging tasks to get right. I discourage my framebuilding class students from using verticals for that reason. An English style frame that uses a wheel with internal gears is a great place to begin.

There are lots of different philosophies on how to fixture (or not fixture) frame assembly. It is difficult to make an accurate rear triangle without an accurately built fixture. It is possible get it right with just a true wheel and a long straight edge with an adjustable screw. That method requires you to spot braze, check, adjust and fully braze each joint one at a time.