I love talking to others about potty training (and the like). I guess this is exactly why I got my degree in Child Development :) The baby and toddler ages always interest me. I enjoy hearing what has worked and not worked for all my friends.
As for me, I was so excited when I realized that it will be 8 months of no diapers in our house :) For those of you asking what worked for us, here it is :) Disclaimer: I know that every child is different and maybe I have not met my match yet. It is not like me to publicize my opinion out there where it can be offensive to others...this might end up being the first and last time that I do this :)
We kind of have an open door bathroom policy. Our boys have always seen us use the bathroom. I think it is healthy for children in diapers to see that their parents/siblings use the toilet :)
We start around 2 years old (18 months if you feel ambitious, or even later than 2 1/2 if you feel you or the child are not ready) with encouraging the child to go on the toilet, we do this randomly or after changing their diaper, find what works for you. With Brycen I would ask every time I changed his diaper, "do you want to go potty on the toilet". Some days I would even ask if he wanted underwear or a diaper and let him decide.
1st time on the toilet: Read books, sing songs, find what excites your child. It will take them awhile to learn the urges that come along with potty training (my boys held it). They might not go potty but it is getting them used to the potty/toilet that matters at this point. You can also try turning on the water or running water down their legs as they sit on the toilet.
I talk with them about being a big boy(/girl, if I had a girl). Then right around 2 1/2 I decide a time that will work for "potty training" (a time when we can be home a lot or at least no road trips for about two week, etc). I tell the child all about the day, however they understand time. (days of the week- on Thursday you get to wear big boy underwear, count down to the day- in 5 days we are going to wear big boy underwear..then count down each day, etc.) With Brycen I told him we were going to go potty on the toilet all the time when we got home from grandma and grandpas house (he had over a week of me preparing him).
We go straight to underwear (it is important that they really like the underwear they will be wearing). The reason that we do underwear is because the child knows when they are wet and can learn the process faster. We also do underwear at bed...and plan to wash sheets frequently for about a week (although our boys stay dry more than not, even at the beginning...if they were to wet every night we might have changed our opinion). We also go straight to the big toilet (with step stool and the kids seat on top). We do this really just because the idea of the little toilets disgusted Scott. I have found that the kids like to be big like us anyway.
Jacen received a book for his 2nd Birthday from a friend called, "My Very Own Potty!" by Fisher-Price. He really liked this book. The book even came with a stickers and sticker chart with Sun-Sat. For Brycen we found a potty chart online at google.com by searching "free potty charts". I let Brycen choose between a few of my favorites. We give stickers for having success on the toilet (the first few times Brycen wanted a sticker and he didn't go. I told him he could have a sticker on his hand for trying but that stickers only go on the chart when he goes potty in the toilet. I like this approach because I don't like to focus on how many times they don't go but rather that they sat on the toilet and tried.) Both my boys took awhile longer with the poop...which means poop in underwear...yuck!! I then use chocolate as a bribe, because that is just gross! Chocolate seems to do the trick after awhile.
I tried having both boys naked when potty training because I understand that they can confuse the underwear for a diaper. It didn't work for us, I became the "don't touch yourself" police. Just underwear was perfect for us. With my boys I started with a reminder every 15min. If they didn't go sit on the toilet one time then the next 15min, I would say it is time to go sit on the toilet. I found that with Brycen all I needed was to say "do you have to go potty" every so often. He would get mad at me if I suggested it too often so I quickly stepped back a bit. We still to this day go potty before we ever leave the house, and before going to nap or to bed. The boys have this routine ingrained in their heads now.
Something I also do, is wait for them to ask for the chocolate and stickers after the first few days. They will start going for the praise and not for the reward, this is key. (I would take notes of accidents and the successes that didn't get stickers on another sheet of paper.) Be sure to always praise them for their efforts. If they go on the floor let them know that you are sad that they didn't go in the toilet. I am sure to tell their dad how big they were that day when he gets home from work...or I have the child tell him that they went potty/poop on the toilet. Again we don't focus on the negative. We also call grandparents tons for the praise from them :) Good luck! Feel free to ask questions because I feel like I could go on and on..and if you know me you know this is true :)