Runescape powerleveling can mean two different things

A Google search will find all kinds of sites with that will
train your account for you. This breaks rule 6, but several
people still do it. The majority of these sites are just after
your password. They will charge you a certain price in real
money, and then they get your account password. This is as
risky as it can get. Most of these sites will offer “Live Help
Agents” that you can talk with to help you with your “orders”.
They will just reassure you it doesn’t break any rules and
convince you to pay them money.

The other meaning to Runescape Powerleveling is when someone
continuously trains and gets a load of levels. Therefore, if
you hear someone say, “I am going to do some power leveling”
now you know what it means. I am going to give you some
training tips, because I would rather help you level yourself,
than use the above method. When I find those kinds of sites, I
report them to Jagex. They sell more than just levels; they
will also sell gold and items. Although Jagex has put a trade
limit on, they have found a way around it.

The best place to train in my opinion is the Stronghold of
Security. Located right in the middle of Barbarian Village.
There is a hole in the ground around where people are always
mining. If you right click it, it will say Climb down Entrance.
This Entrance is the entrance to the Stronghold of Security.