Thank you so much! I am very new to the SDK as i only have like 70 hours, tips like this really help to make my maps better, also taking the time to put links in for me is really helpful as well. Ill get learning, thanks so much!Thanks for showing interest in creating maps! We definitely like to have community made maps on the servers.
I'm assuming you're new to mapping so maybe I can offer you some tips.
First of all, when you're creating arena maps for servers you need to put space in between your arenas so that the plugin can partition spawn into arenas and so that players don't hear shots from other arenas. Here are some guidelines for making these kinds of maps.
As far as the map I definitely like the idea but it can be hard to judge a map without actual play testing. One thing that you might want to consider is if the scale is right. You want the map to be big enough so that players can't just rush from one side to the other. Another thing to make sure is that players can spawn safely and not spawn in line of sight. You want to consider how the angles at each place of cover will play out and what may make certain places annoying.
You can also improve the texturing on the map and add more detail. For example, for the red stone cover on the far right the texture can be shifted down so it looks like two minecraft blocks instead of cut in half. The diamond texture can also be repositioned or scaled. If you are applying a texture and you want it to match when you are going around a corner, you can hold the alt key on one face and apply it to another and the textures should line up.
I would highly recommend watching this TopHATTwaffle playlist which goes through all the basics. There are several things in your map that you may want to consider making func detail for better optimization/compile times. Also visibility is incredibly important on 1v1 maps. The cobblestone texture may or may not make it harder to see player models. Getting the lighting right is also helpful. Also, in order to make custom textures work you need to pack them with your map using a tool like vide. You can also watch more helpful tutorials on 3kliksphilip.
Once you feel happy with your map feel free to add me and I can help you play test. Also, I would recommend posting your finished map on game banana and the steam workshop for more feedback.