I'm quite new to DOTA and here's my advice:
- Start playing against bots for a better understanding of how store works, feeling the controls, adjusting configuration based on your exp. I would also recommend you play with only one or two heroes at first.
- Watcch videos of commented playss. You may learn a lot about how and why things happen.
- Once you can beat bots in easy/normal, jump online. Don't be afraid of online play. Bots are much better than what you will probabl7y find online (they actually team work).
- Be patient, try to stay alive, but don't be a sissy coward either. This means: don't go alone against two or more people, use the towers to your advantage, don't rush when it's not clear that's what you need to do.
- Forgot to mention earlier: don't understimate the power of creeps. Creeps are essential to play this game, both to defend and attack. People think creeps are there just for farming purposes; they're not.
- Try to understand the role of your character. If you're a support, you need to help your carry and your whole team. don't worry about losing some gold and exp if that helpss your carry and your team.
- Finally, don't worry about winning too much. Do your best, but this is team work. Many times you will do awesome and will lose terribly because your team suck. Other times you will suck and your team will do fine. Just enjoy the game as it comes. Don't worry about sucking and don't ever believe you're under control of the situation. It will take you months and yearss of playing to reach that point.
Off the top of my head, these are the most basic tips I can give.