I ran around your map for a bit, and had a couple of thoughts. Firstly, and probably most glaringly, your map is extremely flat, with almost no height variation except for around mid. However, some of the floors in your map aren't as flat as they should be, with little bumps between brushes, such as this:
These aren't good because they can affect splash damage dealt by explosives.
Another thing that you'll notice in this screenshot is that the timer is set to four minutes to start, instead of the standard three. Generally, unless you want to expressedly try something different, you'll want to keep to the standards of map design; the rules exist for a reason, and generally, especially if you're just starting out, shouldn't be broken without reason. You also are using mainly the grid dev textures, which are quite grating on the eyes; most people prefer the reflectivity dev textures, usually between 10 and 60 percent reflectivity. Most of the time, team coloured textures (whether dev or not) are kept to things you want to draw attention to and buildings that a team might hold.
Another large issue is your capture zone; not only is there no indication as to where the capture is, it is extremely small. I'd suggest looking at other maps to see how they indicate the capture zone (often with hazard tape overlays) and how large the capture zone is. Speaking of overlays, I noticed you didn't have any overlays underneath your pickups. You might not have noticed, but in every official map there is an overlay underneath every (group of) pickup(s). You can find these overlays in your texture browser by filtering to "patch".
Anyway, that's pretty much the extent of what I have to say here; I hope you find at least some of it useful! Feel free to ask me some questions and I'll try my best to answer them. I'd also suggest getting your map tested on the servers (
you can find out how here) to get direct feedback from players, and even play the map yourself! I can see this map going places if you continue to work with it!