I always give a treat to my boy to encourage him to do the correct thing especially when it comes to learning where to do his business. We live in a high rise so litter box is my best option although he has learnt to do his business outside when we go out for walks which is wonderful. Even if he goes 20 times a day to pee in his litter box, I still reward him treats each time when I do see it. I just break the treats in to smaller pieces so he won't have too much when its totalled up.
As time goes by, he just gets more and more reliable and even when I am out, he is very reliable. Treats are the best thing to win their little hearts and a good training tool. Oh not to forget, they love lots and lots of praise and pet on the head. Mine looks like he is smiling each time I reward him hehe.