On our desktop systems answer to flickering in Paint event was to use double buffering. .NET Framework supports it out of box and if you do not like built-in solution, there is quite a few solutions out there. Most of them use SetStyle method in order to inform Form that custom draw will be performed.
If you try that in Windows Mobile, you have a problem. Not only that there is no SetStyle, but you must remember that your application needs to work when rotated (all mobiles with keyboard need rotation too).
Solution is to create your own double-buffered class. Whole idea is rather simple, create bitmap with size of control (client area only) and draw everything to it. Once you have drawn everything you need, paint this bitmap over your control. Since this will be done in single operation, no blinking will occur. Be sure to override PaintBackground method also. If you forget that, you will still have flicker since painting will be done in two passes. First pass will be erasing background - usually in white, and second pass is drawing your buffer. Such sudden changes between white and non white tend to be noticeable.
Here is sample code that I usually use.