I mean that you use allegro (if you are newbie).... I simply think that Allegro is very nice for this kind of isometric designing... "easy" and good practise.Actually, if someone "really guru" would like to answer, how powerful are this algorithms of Allegro ? Like pixel drawing and bitmap blitting, are those VERY SUPERB FAST, or just "ok... ye, you can create slow games but never quake" ?
And then to original question: HERE ! You can find lots of GOOD tutorials here at gamedev from under tilebased-games programming area. Actually I never found any tutorial with everything (like full source code and explanations), but I found lots of good docs for theorem. Also check Flipcode.com, they have some nice tutorials too.
Because you are using Allegro, I would like to suggest that you first try to go Allegros homepage and check "add-ons" section, and download FPS2 (or DPS2 or something like that) TILE-ENGINE add-on. It's VERY FAST (mhmm.mm... not fast enough for me, as some people already know from my question ...), atleast in 640x480 256 colors its good, and everywhere under 640x480 it works with whatever color depth.
So its very fast and easy to "build" under your program. It also includes mapeditor and very nice documents (even I understand that stuff .
If you want to build your own engine, I would suggest you to practise from this engine, because it has partly documented source code ! (open source project ?)
Hmm... What can I say ? Good luck ! I'm trying to create scrolling-engine which works with 16bit colors and 640x480 atleast 30fps, but haven't got luck so far 
Maybe it's partly because I don't have right now computer which I could use to program anything 
