I've been playing DOTA 2 for close to 6 months now. I'm still terrible, but there are survival tricks.
Read this:
http://steamcommunity.com/sharedfiles/filedetails/?id=123364699
Welcome to Dota, you suck.
It tells you a lot of useful information, including basic survival tips for playing right, and encouraging you to continue, even through your mistakes. As long as you are actively trying to get better, you will be able to ignore a lot of the hateful comments.
For your first 50 games or so, you will be playing with either complete newbies, or people coming off of the original Dota from WC3. There are a -lot- of assholes who claim they know better here, but frankly most of them will be just as bad as you. It's easier to blame someone else then admit you made a mistake.
I found around games 100-200 you start running into more reasonable people. You will still run into one or two raging assholes, but the amount of times you do is dramatically decreased.
Around the 300-400 game mark, I'm finding more players that just are trying to learn and play the game. We're still all terrible. We're completely awful compared to the High tier, but it's now just amateurs playing.
The advice above is good too. Playing with friends is a lot more helpful, as they can give you criticisms and observations that are not tainted with the desire to win.