I hope you intend to party because you won't pass lvl 20 if you don't (beside if you are a Beastmaster). Soloing after lvl 15 is very long and boring, you will only solo in the beginning. At lvl 30, you can almost die (and will spend 10 mins on him) from a monster that will give you like 25 exp (and you need like 5000). So I do hope you want to party but for the solo part, forget that.