This is my first map, so don't knock me too hard. I know things are wrong as far as lighting and blending of ground textures, but I don't know how to do that stuff quite yet. It's a fun little aim map and I hope it can be enjoyed by all. Any questions just ask me! :)
I named it aim_freestall_beta2 because I wanted to keep the original in case I get really good with mapping and want to transform it into a bomb map as well.
Pros: If this is your first map then you did really well. Seems you have the basics down pretty good. Now just learning more about texturing and lighting you'll be on your way. Also pretty good brushwork for your first map.
Cons: Like you said, the lighting and ground texture needs some work, but you'll get the hang of that in no time. It seems a bit to open also. Meaning that players need more cover in the open areas.
Improvements: Again, lighting. An outside map need an entity called light_environment. Click your entity tool and look for light_environment. Place one of these in your map and experiment with the settings. Check out this tutorial on lighting. http://www.fpsbanana.com/tuts/1924
Also there are some good tuts on texturing on this site. One thing to remember is that any texture that has the word BLEND in the name should only be used on a displacement surface, meaning a surface that has been modified using the displacement tool. Check out this tut on displacements. http://www.fpsbanana.com/tuts/260
Notes: I hope these tuts help, and again for your first map you have done a god job. The more you map the better you get so happy mapping.