If you prewash your fabric, starching the fabric before cutting will help stabilize it and reduce this problem. I don't prewash and find there is enough sizing in the fabric for my Bernina 1230. I piece without a walking foot and don't even use the straight stitch plate.
Love the glue stick idea; might try that myself!
Meanwhile, though, another technique that helps even out the feed is to hold the strips together above the presser foot. You can pin, but when doing this I just eyeball. For example, if you are sewing two 42" strips together, you place the strips under the presser foot and do a couple of stitches to start. Smooth the two strips out together for about 12", pinch them together in your hand, and feed to the presser foot from above. This places a little extra stress on the bottom layer and a little less stress on the top layer, which tends to even out the feed.