At least in DotA there were some hereoes capable of getting first blood at level 1 even before the creeps arrive on the lanes. I've seen a Huskar tank a midlane tower to just fill his enemy up with Burning Spears. Huskar runs away with like 2 hp, his enemy dies shortly after, cool! Some people play techies by buying some clarity potions and immediately teleport onto the lane to put some mines there and score the first blood. Juggers spin is mentioned above.
Or you can just simply go for the first blood by taking 3 - 5 people to a single lane in the beginning and just disable the shit out of the enemy and easliy score first blood.
I usually play pretty agressive on the lane. Trying to score hits on the enemy hereos as often as possible. Depends on who you're facing on who you are. A tank with a ring is pretty much useless to harass.
Silencer can eat the enemies mana and hp with curse of the silence. Some hereos should really get bottle and often check up on the runes. Bottle a haste or invis can save your life, bottle a dd and you can score some kills. Theres always something to do on the lanes beside getting Creep Kills/Denies. Sometimes you just have to check up on your friends, being prepared for the ganks.
Lim-Dul: The reason I usually buy Vlad is because it got such a good recipe. To start of with a ring of regeneration (2+ hp reg) or Ring of Bassilius (enhanced mana reg). Then later being able to get a pretty good life steal which also applies to your friends. Since it's an aura you can have a satanic together with it, or maybe you don't wanna trade you hereos own orb. Which was the case with Ursa or Magina.
Hope not they changed the system. ^^
Sorry for tl;dr