i don't think you should go yet. it's best to go at level 35 that's what i would do. i started around level 28 and i died a lot of times. but if you really want to go at level 28 you should bring a partner.
My life wizard has been doing GH on and off since level 20. She finally finished it at 59. I decided that my other wizards weren't going to do it until Wintertusk came out. My death is working on it right now and she's a level 43. It's much easier to wait until you are a higher level.