First thing to do is to look at lots and lots of pictures, and handle as many of them as you can before committing to build. Get the books. Be aware that it's a 100-200 hour project, for even a simple build (no carving or engraving), especially for the first one.
Stay away from styles with complex curved lines to their architecture, Lehighs, Bucks, and Berks should be out of the running.
Flint will present greater challenges to shoot well than percussion, but is slightly easier to build.
Lehman's and Ohio's are generally shorter, and somewhat slim in look. Ohio Vincents are most commonly seen in half stock, and in percussion.
Many-pieced PB's with lots of complex shapes and piercings will add considerable time and complexity to the build, as does a more complex release mechanism. Those are common features of Bedfords and Emmitsburg, and they just don't look "right" without them.
A poured pewter nose cap is easier to do than the complex shape of a captured RR, but get the dam, seal, and pour right, or you'll have a dam mess. Those are more commonly seen on half stock rifles than full stock.
Tennesee's and SMR's are often seen as Schimmels or Poor boys, in smaller calibers, and with minimal embellishment. PB's are often grease holes in the butt. Much easier to do than a complex PB.