my dd is almost 3. We started using a chart a few moths ago and she has responded well.
I think you need to use the chart to target a specific behaviour. At the moment we have two - one called "Be gentle to your brother" and one called "Listen to Mummy and Daddy".
Ours are not actually sticker charts - we just draw a smiley face on with a coloured marker. This is cheaper, and there is also the advantage of being able to make the faces bigger if you need to get to the end in a hurry (or smaller if they are doing well and can wait a bit)
To make the chart I just draw a long, horizontal rectanlge the length of the page. At the end I dra and write what the 'prize' is (DD gets to choose - she usually chooses eith chocolate buttons, a chuppachup, or a bottle of apple juice!)
At first you have to be a bit over the top and give the smiley face for little things, so they get the idea. I also make sure I always mention the real reason for being 'good' eg, "It makes your brother so happy when you are gentle" rather than just "be gentle and get a smiley face"
Once they get to te end they need to get the treat straight away. For the first column of the chart I would try to make the faces quite big, to ensure they get the prize quickly, so within the first day or so.
My DD loves her chart, and she shows it to people and is very proud when she gets to the end. I think the short term sucess depends on how hard you try to notice them being good and make a fuss of them, and the long term sucess depends on you constantly making the connection for them that good behavio equals not just a treat, but also happy family members!
HTH!