Use the right sticker in the right color family for the job. Tie the individual stickers together by boxing them, matting them, or joining them with another straight line sticker. That way they are not floating 'loose' on the page. This page to the right also shows how you can anchor stickers on a border with a line drawn as a clothesline. The bottom border also features a torn cardstock snow bank scene with handmade signpost and sticker tree.
Landscapes are lots of fun to create as bottom borders.
Another example of a landscape scene is that in figure 10 above. The paper doll girl stands in a die cut grassy yard filled with punch art flowers. Make your border look like your own true-life scenery. Think outside the box and allow your extra-wide paper piecings to be the lower border. This flower pot paper piecing from Windows of Time looks great on this friendship page.