1. Locked doors cause quite a bit of lag time. If you can avoid using them, then try to. In this case, in the room where 6 locked doors are, only 2 of them are needed. Fill the empty spaces with tiles.

2. In the room on the right, try not to make a squiggly tile formation. It isn't very fun to ascend.

3. That launchpad room... ugh. Clustered launchpads are NOT GOOD. If you removed the launchpads and placed maybe two rockets and a switch it would've been better.

4. The laser drone is placed in a cramped space. Try moving it to the larger space to the left, or even in the chaingun room.

5. NaN the chaingun. It would work a lot better. Otherwise, simetimes it kills you as you ascend the pillar thingy.

6. KEEP THE SQUEEZY PART. I like that part. =]

7. Last but not least. The zap drone at the end. Also, the launchpad isn't in a very good place. A gauss would work better, maybe on the left side, between the triangle thingies.

I liked the floorguard placement and mine placement. The tileset needs work. 4/5, because it was excellent for a first.

This is so cool.

another few tips :D
1.Often most "noobish" maps involve a very set path that is obvious to the eye.try to make your maps more open with paths that arent immediately obvious.

2.Conformity
Try to have a set theme to a map instead of "one of everything" this is a very common trap for fledging map makers.From this map i had the impression that you put one of each enemy just for the sake of it.Realise that there are circumstances where some are better than others.

3.This one is surprisingly important. Most people just dont care.even fewer will rate your maps. make a confident post and dont call attention to your lack of map making skills by saying "this is my first map, please rate me good". Saying it is almost suicide.

Apart from that its a damnside better than most first maps, i hope to see some more from you.

P.S to GREATERGLORY , the map is entirely possible, you just need some speed to get bast the squeeze.

A couple things that are hurting you-
-Test- Even if you can't complete your level you should test each part individually. There is a part of this level that is impossible because N can't go through it.

-Enemies- Use enemies only in the right places. I liked this level but in the place where you have the laser drone and the chain gun drone it is very hard. Make should you can at least do every part of a level individually before posting it.
-Clustering- This adds to load time and no one wants to sit there waiting. Also in many situations it hurts the map. Spread your gold out a little and put less total.