TOO LONG, DO READ

Well you start with the hero selection. Pick a hero that his talents are kinda OP (example techies gets +251 dmg). Note that the order of the talent tree doesnt match the 10-15-20-25 level scale. Also mages get a 5th skill slot.

Then you have to improvise depending on the skills/buffs you find. You need luck, let's be honest, some skills are way too OP, so, even if you chose a simple stun in the beginning, if it doesn't match your long-term built, you should not level it up, and replace it when your other slots are full (it costs only 100 gold to do that, you dont need to be on the shop).

It is very important to be able to farm/kill from the early game, otherwise you won't be able to keep up till the end. So you have to choose wisely if you will level up something or just discard it.

Let me give you 2 examples of builts. The first one, lets call it a mage built, its a mix of stuns and nukes, with lowered cooldowns, plus some aoe dmg per second.

Drow Ranger has a 50% decrease cooldown talent. Other heroes have 10-20% which is also good.
So, you can start with Regen aura and death aura, so you can farm fast. pick nukes and stun for skills. Rush radiance octarine. get the lower cooldown passive and the magic dmg boost. You will literally walking around hitting nothing and killing mobs.
By the end of the game you will have 2 stuns (or stun/hex) and a (high dmg) nuke, lets say Zeus' W skill. Pick a ulti that has a low CD.
You will end up with 50% + octarine + passive (i thing 35%) cd reduction. You will perma-stun a target, while nuking him, and while death aura/radiance will harass him hard. If you are really good you can continue with Etheral.... I hope that you do understand the HUGE dmg you will deal while the enemy cant do sh1t....

A second built could be the huge attackspeed/bash built. You will get a hero with high dmg/attck spd talents, rush lifedrain so you can farm and then go basher, moonshard. You will need the dmg passive and the endurance.
You will end up with huge attack speed, high dmg, and almost perma-bash, while you lifedrain really high amounts of hp. Good skills for that are Huskar's passive, Troll's passive, Ursa's active and passive etc.
Endgame you will need daedalus, mkb, satanic.


If it's the team mode, you can keep in your backpack drops your team needs (and you dont) and hope that they do the same :). Dont be afraid to ignore skills you dont like. Also dont be afraid to pick a skill that can lead to a kill, even once. You will delete it later, a stun level 1 can be really profitable until you get the skills you want.

Last tip. Blademails (active/passive/items) are really important part of the fights, so use them and be careful of the ones who use them.

I hope I helped a bit, remember the most important is to figure out early what built you will choose, and to manage to farm fast early, dont forget that everything can be reversed. I told you 2 popular builts but there are many many more.
Enjoy