For newcomers to the genre, this is a very complex game with lots of mechanics. Don't let that discourage you from playing though. Dota has a devote community with guides and help around every corner. Starting may be overwhelming but once you get the basics down it's not so bad. You never stop learning though!

Learn from your mistakes and don't let other people ruin the game for you. Many are passionate about this game and they will say things in the moment, but keep moving on, focus on the goal and you'll be just fine.

Good luck, have fun! :D