Quote from tr0nicDisplay MoreMap awareness is key to success in dota. Sure Wards are VERY helpful, but you need to "try" to keep track of your closest enemies (your lane) as well as the 2 other lanes. I pretty much move around the map not looking at my hero, but AHEAD of where I'm going, while looking at the mini-map. why? because you can spot enemy color in the map quickly, even if they are only seen for 0.5 sec. Always look at your mini-map ALWAYS!
Rune spawns at 2 minute interval 0, 2, 4, 6, 8, etc. Make sure you know what you're doing if you are close to a rune spot in that timeframe.
Learn to pull neutral creeps into your friendly wave of creeps.
Learn to stack neutral creeps. ( doubling, tripling the amount of neutral creep to increase farming if you have enough nukes or a carry to support )
Like Sentura mentioned, learning the map and it's hidden foggy paths will save you numerous times, and if you die, you will have gained maybe that 3-4-5-6 seconds necessary for backup to arrive and make 2 kills for 1 death.
Communicate with your teammates, ping in the map, draw lines, say predetermined messages with the radial menu (not sure but I think it's T or Y by default)
One last thing, try to buy your items as soon as you got the money, if you know you're going to die 100% and you have only 200 gold in your bags, try to buy Teleports (probably the most important item in the game as you get matched with better players) ALways try to carry a Teleport if you are doing your things in the jungle, farming in a distant lane or even when you are pushing in case shit hits the fan and you gotta run(little juke and hop double tap teleport to tp back to base) ---> Enable Double tap self activating key in the options. Works with potions, tp, and few select skills.
If you have no vision of adjacent areas you can watch the minimap all day and still get ganked. But yes, carrying a teleport scroll is key to getting out of sticky situations.