You didn't mention anything about prepping the spokes and rim before building. I assume you put a little grease on each rim hole and some kind of lubricant on all the spoke treads? I use Spoke Prep from Wheelsmith but a number of different lubricants can work. For example a thicker oil like Phil Wood. And I've heard of linseed oil too (because when wet it is like an oil but as it drys it keeps the nipple from turning like Loctite. In fact almost any oil will work.

Different wheel builders have different methods and philosophies for their choices. My preference is for the pulling spokes to have their head in the inside and body on the outside on both flanges. When I set up to build a rear wheel, I like the cassette or freewheel threads to be facing me when all the pieces are laying on a table. I do the inside spokes 1st and start lacing them to the right of the valve hole when it is in the 6 o'clock position. By always placing them that way I am less likely to make a lacing mistake.