Although the diagnostic algorithm of a suspected bone or soft tissue tumour, as well as the biopsy itself, are well defined, avoidable errors still happen. Major flaws might lead to unnecessary tissue contamination resulting in amputations or recurrences. In the current review we will focus in particular on biopsy guidelines and possible biopsy-related problems such as haematomas, sampling errors, and postoperative fractures. Finally, we will provide ten simple rules for a successful biopsy.