potty training with little success

Why doesn't someone tell me that it's not just terrible TWO that is hard to cope but it gets worse when toddlers reach three? I'm working on potty training Clayton and it hasn't been very successful. In fact, it is getting messy and frustrating. Sometimes, he can pretend he's not listening when I give him some firm instructions on what to do when he wants to poo and pee. I'm still thinking of ideas to succeed in this for life will be easier for us if he's potty trained before our Hawaii vacation. Mommies out there.... any tips on this?