Enemy Creeps
Farming creeps sent by the enemy team is the best way to get gold. Fight creeps that are weak against your hero, and work with your teammates to defeat as many creeps as possible. Creeps drop items that can be used by heroes. Share items you don't need with other players and have them do the same for you.
Neutral Creeps
Neutral creeps are scattered throughout the map and can be defeated by both teams. They are worth gold, items and experience points that increase your hero's level. Neutral creeps show up as small black circles on the mini-map. Watch for this circle, get to them immediately, and kill the creeps as fast as possible. Work in groups of two or more. This will help you kill the neutral creeps faster and protect you in case an enemy hero shows up to kill the same creep.
Getting the Last Hit
The hero that strikes the final blow on a creep is the only team member who receives gold. Since you will fight with friendly creeps most of the time, use any instant-cast spells you have to finish off an enemy creep that is about to die. Don't let your team's friendly creeps get the last hit. If you do, no one will get the gold.
Sell Junk Items
Many items you find from creeps provide little benefit. Sell these items to one of the shops at your base and use the gold to buy items that will be beneficial.
Pooling Gold
Pooling gold is a strategy where you designate a hero on your team that everyone will give gold to. The idea is to develop one hero with enough money to buy strong weapons and armor that can benefit the whole group. This requires teamwork and is best done in clan matches rather than in public games.