This book: Oh Crap! Potty Training: Everything Modern Parents Need to Know to Do It Once and Do It Right by Jaime Glowaki. was such a great resource for me and my wife. Circumstances are different between families so we kind of used it as a template but my daughter just turned three and is able to go find the potty on her own and go #1. Still working on #2 but that ones a little harder.

But my top piece of advice is: Stay consistent. Create a routine and stick to it. Teach them to seek out the bathroom, after waking up in the morning, before outings, before bed, etc.