Your titles are good,but tweak them ever so often to see if you get different response in views. Make each one different(dont always start off with original watercolor etc-for example).
Change to different wording,etc.
Your tags need to be tweaked. What would a buyer put in search to find your item?
Ex: Oil painting,personalized wedding painting,space shuttle acrylic,etc.
Tags are best when they are more specific. Hence why phrases work best. You can use one word tags,but I find phrases put items in top couple pages of search.
Try some new tags on a few items,just to start...give it a few hours and I bet you see higher search results!