I was taught if you have an offence against a brother, first go and speak to him alone, so that the two of you have a chance to work it out.
In reality, I've never known that. I was grassed up to the Elders for something I WASN'T doing by someone who I never associated with in the Congregation (I found out later). She had no grievance with me, and if it wasn't for the fact she was a dub (and so was I at time), where else could she have gone to cause trouble over a 'rumour'?