My personal opinion and what I've found works (with both of my kids... can't be that much of a fluke! haha) is turfing nappies altogether. No more at all - EVER! My kids were put into undies, told about telling mummy or Daddy when they needed to go to the toilet and we went from there. I didn't ask if they wanted to go ever, I gently reminded them every so often that if they felt like they needed to go, they should tell someone. It worked within a day both times. My children were day trained for whizz in under 24 hours (DS was just over 3 and DD was 27 months). DS was totally day and night trained including #2's in 2 weeks, DD took 8 days.

Yes, it can be messy. If you have undies on the kids then you don't have to wipe up poo, although you do have to wash their undies... no big deal. With bed wetting, I had 2 of those pads ontop of their sheet seperated by towels (so I had towel,pad,towel,pad,sheet,mattress protector). If they wet during the night, I'd rip the first pad and towel off and they'd have another underneath. Rarely did they wet anymore than once a night, but there were 1 or 2 sheet changes.
It was so much easier than I ever anticipated. I honestly thought it would take months and months. I put it down to the kids believing that they were in control, and the sensations they got to feel early on being wet and dirty... they got to realise very quickly that it wasn't a nice feeling and if they wanted to avoid that, they should go to the toilet.

Both of my children had alot of toilet experience before we started training. They'd come to the toilet with me often, they got to flush it at times, we'd watch the water swirling etc. I'd always explain what I was doing while sitting there.
Another big motivator for the kids was stickers! I got stickers for the toilet room that they got to stick to the seat they had to keep it all in the one area. They were so excited when they got a new sticker and Mummy and Daddy made such a HUGE fuss whenever there was something done in a toilet.
My kids also just didn't DO a potty. We bought one and had it for AGES. They played with it, but were not interested in using it at all. I ended up getting a step for DS with the seat attached (the red yellow and blue bambino ones). They were much happier as they were using the big toilet just like Mummy and Daddy.

I could have been very lucky. My children were both very ready when we started. I didn't want to try them too early but I didn't want to leave it too late. Every child is different though and that's something everyone has to remember. My kids were 12 months apart toilet training age wise, but I worked around when they were ready.

Good luck with it!! It's a little stressful at times, but when your little one is ready they'll pick it up quickly