I don't mind first posters coming here for keys, BUT they should at least go through the trouble to add the person that's giving the key, not telling them to 'ship it' to them. If anyone wants a key, add my steam http://steamcommunity.com/id/renethetrue/. I got about 4 left.
1. Forget about winning your first 50 matches. Unless you are a veteran RTS/LoL/DotA player, alot of concepts in DotA2 will be alien to you.
2. Dont MIND losing. The reason the DotA community is sometimes known for having a vile playerbase is because alot of people are little shits about losing. It's about getting better every match, not winning each one (although that would be nice)
3. Someone being a little shit to you? IGNORE THEM! There is litterally an ignore button on the scoreboard, it's the 'sound icon' next to a persons name.
4. As a new player, try to pick ranged supports/gankers. Try to avoid farm-heavy carries untill you have last-hitting down 100%. My personal tips would be playing Windrunner, Jakiro, Lina and Lion.
These four heroes give you a basic idea of how to be an effective stunner, AoE damage dealer and a disabler. This is a quick way to learn how to be an effective team player.
5. Once you think you know the basiscs, try a new hero each game! Sure, you can 'stick with this one becaue he seems nice'. But then how will you get to know the rest of the line up if they are used against you? Know your enemy!
6. Read a guide to the hero that you want to pick. Preparation is half the work!
7. Find a friend. Got someone in your friendslist playing DotA? Give him a call! Most people in the DotA community are eager to teach, whatever reputation this game might have because of a few bad apples.
That's just some stuff from the top of my head. If you are European, add me at Renethetrue on steam.