I can recommend this guide: Print Quality Guide - not having all details, your problems might IMHO relate to Overextrusion, Overheating and/or Curling/Warping. Also, a problem I had once, is retraction settings, more specifically the extra prime amount.
@ViperZ: Regarding the dislocated print sheet - had the same, did this - seems to work (but have only done 4 prints with it yet).