I recommend more spokes in the rear than in the front, simply because the front wheel is already very strong and sees less stress. I do like the offset rear rim; it is easier to tension, and highly dished wheels don't hold up for me and dont feel right out of the saddle. I prefer Wheelsmith butted spokes and aluminum nipples, which seem slightly easier to build and are a tad lighter. I do not recommend straight gage spokes, which simply make inferior wheels.
I have built wheels around Shimano ball and cone hubs, which these days are crap. Son, Phil, and DT Swiss hubs all were very nice units. The DT hubs are not as flashy as the others, but seem like a good value for a premium hub. One set I built on VO hubs, which don't have very smooth spoke holes, but otherwise OK. If you do radial lacing, make sure it is a forged hub, and don't do it on a drive side, disk side, or a dyno hub.
Mostly I recommend following a written procedure, like in the book The Bicycle Wheel. Priorities are 1) keeping the wheel round at all stages 2) continuously make tension more even 3) make the weel straighter by tensioning only the looser spokes 4) tightening each spoke only a little at a time. Let it take time, and use a tension meter and sound to judge tension, spoke prep or linseed oil on the threads, and machine oil on the heads. Also, keep a sample wheel next to you.
And most important of all, you simply MUST be able to read the hub logo by looking through the valve stem hole!