If it's a Cessna 150 or the like, use Halfords best
OK on paintwork, but does it not cause blooming and other damage to perspex?
Use an aircraft cover for protecting the transparencies, then turn the a/c into sun to warm up the perspex whilst mechanically removing the worst of the frost. Then use cheap car de-icer on the wing & tailplane surfaces. Allow at least 30 mins to do an a/c properly on a frosty morning.
The other problem I find at this time of year is that the interior gets damp and combined with warm, moist exhaled breath causes chronic misting up inside. We use a sponge fitted with a chamios cover (also from H*lfords) but you have to keep wiping and wiping until the heater gets going, usually well into the climbout.
The alternative is to pay for hangarage, presently around £3.5k p.a. round our way. (if you can get it!)
TheOddOne