Arnold. To use Razor, you should pick skill number 2 and 3 for the first time. It makes Razor move and Regen HP faster and ready to battle another Hero with Chain Lightining. Gondar is a Agility Hero same as Anub' arak and Razor. It has ability to be Invisible for opponent. That ability is very useful to escape and killing another Hero. Shuriken and Track are use to finishing opponent Hero until die. Anub' arak has a powerful area stun that deal large damage. You can use that skill to escaping and chasing. Otherwise the mana burn ability can be very useful on the first game.
And for Tiny, you had to pick skill number 1 and 3. For the skill number 4, i think you should pick it when your hero is in Level 10. And don't forget to buy item thet increase attack and movement speed. (Alex MZX)