let him get messy! LOL
i found that the best solution for not only feeding self, but also for avoiding the tantrum that goes with a child who wants to feed himself, but you are hesitant because of the mess... just let him make the mess! :D i cant tell you how many messes ive cleaned up in my sons 27 months.... but its all worth it. it was so much easier for me to just let go and let him make a mess than it is for me to fight with him!
this haphazard, messy eating will not end for a while. my son is JUST starting to eat nicely without making a huge mess. sometimes he will still make a mess. :P i wouldnt really worry too much about teaching him to do it "better" because its just not possible until hes developmentally ready for that. its a complicated thing! :D
so just have patience, and remember that it wont last forever, take pictures, videos and cherish it, cuz believe it or not, someday not so long from now, you will miss it :P