Spray Scotch Guard on each bag before you use it (on the nylon parts only). Just make sure the bag is REALLY clean before using Scotch Guard, or it will stick to any dirt and make it look worse. Each spray application will keep your bag pretty dirt-resistant for up to 6 months. Remove the qee and chain from the bag or cover them up before spraying the Scotch Guard on, and try not to hit the leather and hardware (it’s not the end of the world if you do though, just wipe it off with a clean sponge).
To wipe off dirt, Mr. Clean Magic Erasers work well – they take some patience and persistence if your bag is really dirty though. You can also use a tiny bit of Woolite and a soft sponge and/or Tide pens for cleaning Tokidoki bags.
You can find Scotch Guard, Mr. Clean Magic Erasers, Woolite, and Tide pens in the cleaning products aisle of any supermarket.
Read through the comments to this post for additional cleaning suggestions and discussion of what does and does not work.