I dont use colour filters, I think it really depends on what feature you want to observe as to what colour you want to use under the conditions you have. Houghy has given a good indication in his list above.

I would like to include a light or medium blue filter to bring out the haze in the upper atmosphere. Although from my place a week or two back I could clearly make out the upper atmosphere that was quite obvious on the bright limb no filter used.

Colour filters dont improve the views your already getting of Mars they just bring out different types of detail a little better sometimes at the lost of others.

regards, CS