The best way I found in training my children to go potty was to number one, wait until they were ready. When they are dry diapered in the morning, that is a good indication. Just make sure you are not giving them huge amounts of water right before bedtime.
Second, use a reward system, from the start. If they like sitting on the potty, reward them for staying there longer, give them a book to look at or if you have a potty chair that has a small tray, you can put cheerios or something on the tray to keep them there longer. It sometimes helps to use a minute timer, and give them the sticker after the timer goes off. That is one way to keep them there longer, and then just increase the time a little after a day or two of success in staying on the potty for one minute. I would definately use a potty chair.
Third, use two things - a sticker chart - where they get to choose a sticker to place on the chart for each time they sit on the potty - at first - and then what I called a "potty treat" where if they actually went potty they received a small item of candy. I kept the candy in the bathroom, in a special container. Place it up high so they can't get into it when you aren't there. The sticker chart had squares for each day, enough to show progress and allow for praise for sitting on the potty and going potty. My kids loved the stickers almost as much as the treats. They especially liked putting the stickers on the chart themselves. People might disagree with the idea of giving treats, then you can just use the charts. I found booklets of stickers so they had lots of choices to pick from, with cute stickers that children like, rather than just stars or something like that. It really worked well.