Leveling is a lot faster if you duo or get a small group. Get some leves for the whole group and aim for difficulty and speed bonuses (set the leve difficulty as high as possible and end the leve before 22:30 on timer). Do behest at the leve camp every time it's up (every 30 mins). Ask the other players in the same camp to team up.

People rarely organize full 8/8 EXP parties before 35+ because the EXP before that is so fast to solo. There are EXP camps listed for every level on this site though.

Good luck!