[Andrey]

Ive done instances, groups that simply went after elite mobs, Quests... in all... the old fashioned method of solo killing mobs has worked fastest. As to quests... they can consume more time running around than if you just stay in place and down mob after mob. The quests you want to do are the ones that ask you to down some number of what your already going to down anyway. Don't take a quest that requires you to travel extensively nor one that requires a group to take down. By the time you get the group together you could have had the same xp just grinding regular mobs anyway. Just find an area with a lot of mods at the desired level and have at it... one after the next....