One trick that I've used frequently is to toss the chocolate chips in a bit of flour or cocoa powder before adding them. You can use this tip when adding dried fruit or berries to a cake too. It's not always 100% effective though. A tip that I've been using more lately is a little different. Don't add the chocolate chips to the batter right away. Pour half of the plain batter into the pan; fold the chocolate chips into the remaining batter and then add it to the top of the batter already in the pan. Don't stir both layers together. Bake as directed. This trick works well and I think you'll like the results. P.S. Mini chocolate chips are light enough so that they don't sink to the bottom.