Piperofna beat me to it...lower your fuel tank. If you've flown before and this is your first glow engine plane I partly agree. You should get someone to go over some tuning techniques and saftey procedures but I seriously doubt if you'll crash in 30 seconds, everyone is different, some people need more help but like I said if you've flown before then you should be fine with a cub, except taking off will be scarey (keep everyone away and get some help with this-tail draggers are not stable on take off if you don't know what you are doing) but I would have an experienced flier or instructor there the first time at least. As for the ailerons they should be level. Slightly down will increase lift and slightly up will loose some lift but make them level on all flight surfaces. This does not mean you won't have to add some trim into the control surfaces though.