Welcome to the boards, Thanin.
Although you said, that you'd post a map, when you have something decent -- well, it best if you start posting right away.
There are many gurus here that can point you in the right direction, you will get plenty of tips, what's wrong with a given map, and how best to improve it. But you only get this kind of help, when you actually post a map.
We can't help unless you start posting maps right away.
We've had many newbies that offerred us their first map try - with a few suggestions, first attempts become masterpieces.
So post a map as soon as you can! And again, welcome!