You shouldn't be picking long from a site. If you're going to play long don't just give it up since you're giving them free information and map control. Always worth it to play corner and take the fight since you have the advantage holding anyways.
If you need to peek long from site you should be doing it from behind site boxes where the graffiti is, or in goose, however both of those peeks don't let you see all of long but they cover you from cat.

You should only ever be playing car if they're going to be pushing cat and you've got someone holding long.

To add to this (I agree mostly what Dscigs said), you can/should basically give some long control to the Ts if you're are playing AWP long (especially if you peek doors at the start of the round).
When you start playing agaisn't proper teams they will flash/smoke you to oblivion if you are holding a direct angle to pit.
Also if they manage to flash you out even for a half a second and get their AWPer to pit, you will lose the duel to pit 8/10 times.
It's super common to do an a split (2/3 short 2/3 long) and if you are playing deep long, the short guys will be hard to deal with.
If you really want to play A site (I personally prefer AWP in mid or even b) play from the site itself, so you will not get raped by uti and short.
Learn to play mid properly and it will be more useful for your team since you can get cat/mid control (which is fucking crucial) more easily.