I find that if I add the grain slowly and mix thoroughly as its added, there is virtually no chance of creating dough balls. I do use a long-handle, plastic spoon that doubles as my volume measuring device. After seeing that plastic paddle that Ken mentioned, I'd say that might work better than my spoon. But after 15 years, I've only broken one spoon.
I do have a paddle made out of a piece of 1x4 Alder wood that I carved a handle into. That is only for my whirlpooling, since my small-headed spoon didn't enable me to get the wort spinning well enough.
By the way, I saw a video with German brewers using their big wooden mash forks and they were mixing the mash more like the way a Venetian gondolier paddles and not like a canoeist paddles. Of course, this was in a great big mash tun.