Well I've built a few frames for myself and friends and the two that were for me are about as conventional as it's possible to get! Both are 55.5cm, square (TT same length as ST), horizontal TT, 1" TT AND 9/8" DT. One is 73 parallel and the other 72 head 73 seat, double butted Reynolds or Columbus, all TIG. One is a fixer, the other a road bike. They both ride really nicely.

As a beginner it's good to start with something simple, also to have a reference, but I suspect the classic design is the best anyway.

It's actually not that easy to buy what I would consider a "classic" steel frame like this these days. Most of them are somewhat overweight perhaps because of CEN crash testing or something.