Loops and twists are very annoying, probably the worst thing about spinreels...I also underfill my reels a little bit, as Rob suggested. This may affect distance casting, but it does cut down on the loops. When doing twitchy retrieves, the only thing that you can do is simply keep an eye on the spool and throw a 'cleaning cast' when required (just a long cast, spooling the line back on tight).
One thing I have discovered that seems to help, is when you throw the cast (especially one that will be retrieved twitch-fully - is that even a word?) make sure the rod tip is under water when you start the retrieve. The wet line seems to add more drag and spools the line on tighter. Also, twitch and reel at the same time...this way there is always pressure on the line...dont twitch, then reel in.
Hope that helps somewhat.