Give the campaign a bit time (to get some days of data). Optimize day by day. Check "user activity", cut bad zones, stop bad creatives. Check after some days if there are hours on daily basis that do not generate profit, maybe splittest against another prelander, cut bad OS versions. Try to seperate campaigns by GEO, OS and when you see bad performing "user activity" duplicate without the bad parts. Optimize only one thing with a check. Do not optimize to much in one. Give it time to get enough data. When you have a good offer and a converting prelander, you will be fine in some days...
thanks a lot your messages helped me most since i started doing this
