I used to play DotA in a very high skillset (I played in closed leagues basically for Div 1-3 player, i.e. around the top 200 in the world: IHCS1-2 and DotaInvite, Both in Garena + I've played in countless tournaments in many different teams). That was already about 2 years ago, so I'm sure a lot has changed. I have been able to first blood some of the worlds best players while being alone against them on a lane (even have this on replay somewhere).
I've currently stopped playing DotA but instead play HoN mostly because all my friends play HoN. Also because at the level I played the gaming became very serious. We had training hours and even the most minor mistakes caused a storm of flame within the team (because when you have to chain spells even a ms of delay can cause your whole team to die).
Interestingly my dated skills seem to be very useful, i.e.:
- Lane control: Being able to last hit and deny properly. Not just the act itself, but also when to push and when to deny more. I can still properly hold a lane still i.e. so that the lane wont be pushed towards either direction, (by proper timing of last-hit) just out of the reach of my closest tower, effectively allowing me to last-hit every creep, assuming nobody comes and disturbs this. I strongly recommend you try to learn this as this is the best way to farm. My record cs is something along the lines of 70 creepkills + 40 denies in 10 mins.
- Always keep a teleport scroll with you (especially early game and especially if you have a stun!).
- When retreating, do try to keep an appropriate distance to your opponents, i.e. don't run like a headless chicken, your last stun might allow you to kill your opponent with the help of teammates. There is nothing more tempting than a hero that is almost dead but just out of reach. Using shadows and proper team communication makes this very effective.
-There are no "perfect" builds for any character. It all depends on your 'task' or position in consideration with the team. For example a "minor priority target", usually a tank, does not have to get tanking items, if he notices that he is ignored in team-fights. For example a centaur is usually ignored until most intel heroes are killed. If the centaur gets radi early, the will be a primary target, which makes him more useful (and therefore should then get more health). Same with axe.
- Intel heroes with a lot of damage potential / disable, such as rasta, should always get a lof of HP early, so they can tank some of the inevitable damage.
- Heroes with an damage / attack speed aura, such as ogre magi or venge are greatly under-rated. A ogre magi works great as a disabler, and combined with a good carry hero makes a very strong combination. For example: If your team picks Venge, Moon, Magi, Omni, ES, you would have moon and venge with stacking damage auras, allowing venge to have a huge damage. With magis attack speed + omni spells moon lategame would be rather unbeatable. Es would clear the opponents from creeps and initiate, allowing moon to ulti and go crazy.
- Silence spells can win matches. One properly placed silence can completely destroy the chain of spells the opposing team has planned, therefore a hero with silence should always stay back as to not get caught by the opposing team. Same with significant disablers (blink dagger users).
- My personal rule is to never go to a lane without decent amounts of heal / mana regen. I can sometimes play for 20-30 minutes without going to the base a single time. This allows for more farming and xp gain, as well as the possibility to help your team. I recommend at least a total of 6 tangoos (9 if carry) and 1-3 mana potions if laning normally.
Hope that helps a little. If you have any more "advanced" questions just post in this thread and I will gladly answer.