Heres something that could benefit a lot of players.
new and old.
Early game strategy's!
Now I know it may sound simple, but its something a LOT of players fail to do.
Last hitting and denying creeps. Denying your creeps makes the opponent in your lane gain less exp and much less if there are 2. Last hitting is quite easy. You want to aim for the sweet spot on creeps. In my opinion when the creep has around 90 hp. Go for a hit, if you're ranged chances are by the time your projectile reaches the creep it will have just enough hp to be killed.
Items! Boots and tengos are not early game items. Some of the best items to take early Are.
-ring of regeneration
Early game, the more time you are off lane regening hp. The less exp and gold you will get, the the farther you will be behind. Just these cheap simple items can make a big difference.
Another thing to know, if you are against a solo. Harass them! Take lane domination, keep them off the creeps; And prevent them from last hitting and denying.
If you have a partner with you, tell them to creep pull, (only applicable to bottom lane for Sentinel, or top for scourge) Creep pulling gives you both some solo time, as well as denying their soloer exp.
If you are a ganking hero, Its best to last hit and farm till about level 5. Start roaming when you have some boots. Heros like Potm, Tinker Are great gankers. And great solo heros. Just ask your team who needs help.