breast meat cut up in squares or strips are fine..or what ever part you like...just cut them up whatever size you like them...small-med sizes work best though...
when i cook, i season the chicken itself and depends on how i cook it...it may get seasoned while cooking too..but chicken nuggets can be seasoned before hand..
but really you can season the flour too if you would like...depends on individual taste..
make sure your oil is hot enough too..