Hi Stan,
There is a myriad of free online resources through Colorado State University and other research institutions are available to the public on various gardening topics. An excellent one that addresses your question is CSU Garden Note #617 https://cmg.extension.colostate.edu/Gardennotes/617.pdf  The Garden Note instructs: “The best pruning method is to cut individual branches back to an upward growing side branch. This method of pruning is time-consuming, but keeps the plant looking young and natural. (It refers you to the illustration in “Figure 4”) ...Any pruning that tapers in toward the bottom of the plant will lead to thinning of the lower branches due to shading. To keep the bottom full, the base of the shrub needs to be wider than the top portion.It is common to see junipers and arborvitae that have overgrown their space. Because new growth comes ONLY from the growing tips, branches cannot be pruned back into wood without needles. If the shrub is pruned back to bare wood, it will have a permanent bare spot. For shrubs that are getting too large, it is better to prune them back as they begin to overgrow the site."
Hopefully the above is of some assistance; Good luck with your efforts!