I do a lot of fostering of puppies and i find the crate training is the best way also.
i also use the commands..."Go pee" "Go Poop" and i have my own 4 dogs trained that way so that when i do bring them somewhere, they will go on command, which is so nice.
Some puppies take longer than others to "Get it". i know my oldest dog, for teh longest time i was struggling with her but then all of a sudden seh got it and never had any accidents after that.
have fun :-)