Hey, there is no new is a lot of maps unbalanced, as you all know Dust II is maybe the most balanced map, just because TS or CT have the change to take one of the bombsites easy/hard. The bomb maps is not so hard to make it balanced you can make a site and player can see all the entrances from one point. Example:


Let's take a look what i did on de_dust_pcg, map made by David Johnston (Author of Dust II) for CS: Source. I recreated this map as css_dust3 and i make it balanced:


1. I added stairs to go down or up to the bombsite A. More easy take for TS instead just from the top.
2. I added a connection tunnel betwen A and B, for fast rotations, if the bomb will planted in A and tunnel don't exist you spend just too much go there, and changes for defuse are almost gone...
3. I added a very short for players to escape in case of CT rush from B to the TS base, let me explain:


As you can see the double doors will help the TS player to escape, if put doors at 180* they can see him when he exit short tunnel and can kill him, but in this way they can't see him, also double doors is a "Question for CT: Rush or not after this doors...?".

When you start making a plan start with what is the most important, in this case: CT Base and bombsites.



Keep in the mind, one entrance and one exit [Dust II - B]:


When you make a map make sure the entrances are for coming in and coming out, if a player get stuck and enemy team come? He is death, that is no balance. Make sure the CT for example is close to the bombsites instead too far away or the same as the enemy team.

Why Aztec is not a balanced map?


How Aztec can be balanced?


This is how i see it balanced. And just an example what i see, you should imagine the same next time you watch on your plan, see what's works and what's not.

Rotations
Balanced map need to must have an rotation plan, what if in A is all the enemy team? You need to rotate fast to B
Dust2 rotation:


Train rotation:



Overpass rotation:


Making an rotation system in your map can be the best thing you can do for competitive gameplay.

Open spaces
Hard to keep it secure just because they see you easy. Also small or too short details is not the best way for this.
Take a look on new cache update in CS:GO


As you can see new one have some big open space there and almost everything get smaller. Hard to defense this site like this, don't do that in your maps! Visual looks don't means better gameplay!