Hi

Flat isometric tiles are "easy" to make:

1.  create a square picture (say 256x256), making it tileable (if you don't have Photoshop you can use this excellent tool to make it tilleable, though it isn't free).
2. rotate 45 degrees; this gives you a picture that is 362x262.
3. resize by 50% on the Y axis, so you get a nice 362x181 isometric tile

Hills and walls are a lot harder to make, I don't know if you're going to need them. There are tricks to generate them out of flat images, which is what we did for this tile set. We are working on a map editor that will include the script we used at some point.

For characters (and sometimes for walls and hills, etc), what a lot of people do (including ourselves), is start from a 3D mesh and render it with a 3D program (such as Blender), using an isometric perspective.

If it's purely for testing purposes, I'd recommend getting the minimap demo that comes with a few tiles and a character (though a very limited animation set). However the license of the minimap demo doesn't allow you to redistribute or use them in a released game (but if you got the tile set and characters from our market of course you could :) ). Some characters in the market are free (just have a quick look), some others are not, but they are all royalty-free, meaning you can use them in any projects, including commercial ones.

This website has some free isometric stuff - I'm not a big fan of the art style but hey, it's free so you can't really complain.

I hope this helps

Thanks, the website with isometric stuff is good for a prototype so I think I will use it.

Wade is or will be compatible with Tiled Map Editor (I have seen there is a json format)?

Do you know where I can find someone that draws custom sprites and tiles in a funny cartoon style? I see that many games developed could be sold only with a great graphics and without that they seems only an experiment.

Thank you