Games : How to get gold very fast in dota 2?

I played against bots and its somewhat easy to get gold while playing against bots but playing against human players its very hard to get gold.while im saving some amount of gold like 4000 most of the enemies saved like 6000 and also bought costly things like desolator and shivas guard and i hardly stand a chance against them.so anybody please tell me some tips about how to get gold faster in dota 2 and also about how to defeat enemy heroes easily.thank u