I just potty trained our almost 3-year old boy, and felt he was ready months ago, when I made a 2-day attempt and quit. This time, I started it using a book called "Toilet Training in Less than a Day" and after reading it, decided to do it and never look back! If you keep wavering and thinking you might go back to diapers (or use pull-ups, which make accidents "no big deal,") then the child will get confused and not really take the new system of pottying in the toilet seriously.
Our society, in my opinion, leans too far toward "let the kid decide when he's ready"- very child-centered. What about you, the parent, having to change his diapers and buy or wash them? I think the parent, once she determines that the child shows the ready signs (which are listed in the book I mentioned), should be the one to decide when to potty train. Not a 3 or 4 year old. Some kids would just never get interested and therefore be in diapers until age 4 or 5!
Some of the tips I'll mention here are from the book.
Keep at it- don't look back, train your child in each step of pottying, and even use a doll and have your son teach the doll steps of using the potty (part of the method from the book). When a child teaches another, learning usually happens easier. Also, don't be afraid of accidents- there will be some. Don't get mad at the child, but do express disapproval. "Uh oh, you wet your pants. Do big boys wet their pants?" "No" "That's right, and are you a big boy?" "Yes" "That's right! So where do you go potty?" "In the toilet" "Yes! You are a big boy so now you go in the potty. We don't go pee-pee in our pants. I love you, but we don't like wet pants do we?"
That way, the child understands the seriousness of an accident, but actually knows that it's not a good thing. It can be positive, but you can still communicate your concern for his cleanliness and the importance of staying dry.
Oh, and that's the other thing- reward for staying dry, and have "dry pants checks" every 15 min. or less at the beginning, longer intervals as he can hold it longer- or you'll have a kid going potty every 15 minutes just to get a treat instead of holding it for hours!
The first two or three days we had multiple accicents, and just a few days into using this method, we had accidents very rarely and he started to get the concept of going #2 in the potty (which was another little hurdle for us). He also started being able to tell when he had to go, but it took some trust for me to just quit asking him if he had to go all the time and trust him to know, even at the risk of having accidents. Don't be afraid of accidents- I was too afraid of them. Two weeks in and he's totally potty trained, telling us when he has to go, and holding it until we can find a restroom in a store and everything! It's great! Your son can do it!
When he does have an accident, run with him in his wet pants to the potty so he understands the concept of rushing there when he has to go, as well as practicing using the potty even if he's already let it all out in his pants.
Sorry so long- this is a challenging part of toddlerhood!
Best wishes! S.