Lowbie quests. There are a couple of lowie quests that can be done along the same general route and can easily get you close to 10 in under 20 minutes if you know the way. Gearing for move regen makes this considerably easier. Lowbies these days have it SO MUCH easier than when I started.

Lowbie areas. Depending on align/ability, certain lowbie areas can speed you along so fast in your levels it's absurd. Examples? The Vale as an orc with any old iron weapon and a very basic set able to be gotten by anyone level 3 or so and up. It's even easier in somewhere like FON in the past as a goodie of almost any type.

Ranking quickly is very easy, if you aren't trying to work skills or gather gold along the way. Likewise, working skills or gathering gold can slow down your ranking. Concentrating on just one thing will make it go faster, but will slow down everything else. You just have to decide which is most important to you. I prefere to level up a little slower, and work skills as I go. But if I just want to get in there and start swinging, I can easily do 15 or more in an hour.