Eastern White pine Splitting

Hello all, I make furniture from Eastern White Pine (standard grade). Occasionally, my it may split on the sides when clamped and glued. I have began to tongue and groove the backs, which seems to be working, but how can I keep the sides from splitting, since they have to be clued together? Recently, I have been putting glue at the top and bottom of the pieces, basically rubbing glue on the top and bottom for about inches or so, hoping this will keep any splits from actually starting. Should I seal the intire piece once it is done, then paint it? I use milk-paint, then wax it with a stained beeswax I make, but I may have to seal it before I paint it, then paint it, and then wax it. I need help!!!!! I know predrilling the holes has helped stopped splits from occuring at the screw points, but now I need to stop splits on the ends. I do keep my wood in a basement area, which is pretty dry. Should I put some dehumidifiers down there maybe, or what?
Help,
Bill