You just have to know what to use to power level.
First lets understand what powerlevelign is. Power leveling is getting a high level character grouped with a low level character and having the low level character sit in a safe spot while the high level character does all the killing.
The level caps for power leveling is 5 levels. When I say 5 levels I mean the difference in levels from the low level character to the high level character CANNOT be more than 5 levels. This is true until you hit level 20. Then the cap goes up to 7 levels.
Lets say your level 2. Group yourself with a level 7 character with the level 7 character kill stuff a level 2 would normally get xp for. That is any mob that is level 2-6. At level 7 you should have no problem killing level 2-4 or even level 5's. Kepp killing the low level mobs with your level 7 and watch your level 2 character fly up in xp. You can do this until your low level character hits the level of mobs you are fighting. SO if you're fighting level 5's with your level 7 character you can keep killing level 5's until your level 2 character hits level 5. Once you hit level 5 get a level 10 character and group him with your now level 5 character. Go to the sewers and start killing level 6-8. again with a level 10 youshould have no problems killing mobs 2 levels lower than you. Once again keep killing until your level 5 character hits the lkevel of mobs your level 10 guy is killing. in this case lets say level 7. Once you hit level 7 go to perez park. Bring a level 12 guy on and kill all spawns that are level 9's or 10's or even level 8's.
DO you see where im getting at? this works all the way up the chain. I know it is hard to get 2 accounts and 2 computers but this is the simple way of leveling up solo and level up faster than if you were in a group. If you see a level 14 guy in Perez killing mobs on the street or you see a level 18 fire tanker killing hydras, he is doing that for a reason. He is trying to level up his low level character by using a high level character.
Thisis very hard by yourself. On top of finding someone to level you this way. I got around that by running 2 accounts with 2 computers. I level myself. Regardless stick to these guidelines on leveling and you will know how to maximize your xp in the shortest amount of time and with the least amount of risk to your character.
I hope this power leveling guide helps you folks understand the leveling caps and how it works.