Because I am relatively new to both pursuits, I am discovering that (at least for me) they are very inter-connected... by searching out and playing many guitars and lutes, trying to find ones that were more or less easy to play, ones that produced the sound I've been trying to replicate, etc. I've explored all sorts of variations, especially in the areas of neck configuration, fret heights, set up, top thickness, different strings and tensions, different types of finishes, etc. As my playing improves (very slowly) I continue to appreciate new aspects and look for ways to incorporate them into my building and restoration efforts. I learn about playing by building and vice versa.
To give you a recent example... I was asked to repair a lute and discovered that a very subtle difference in the way the bridge was configured made a huge difference in the ease of playing it... I might not have even noticed or appreciated the "solution" if I hadn't struggled to play other ones.