There is really only one disfellowshipping offense under which all others dovetail: insubordination. Otherwise known as: rebellious attitutude.
You see, everybody is "weak" and succumbs now and then to some offense. It is how you display an attitude about it which is key.
If you fight, resist, argue, self-exonerate, give excuses or otherwise wiggle and twist; you are dead meat!
NEVER ARGUE!
The bottomline is this: the elders have to engage in due process.
1.Establish an offense has been committed. (Somebody reports you and two witnesses are available to testify) Or, you confess. (Suspicion only won't work. That's when they carefully grill you for more data.)
2.Approach you and get your side.
3.Demonstrate the offense by citing scripture.
4. Determine what your state of mind is concerning the offense.
5.Act to bring the matter to an end. The end is determined by YOUR ATTITUDE.
A meek attitude, mildness, passive-resistance, non-confrontational curiousity about the nature of your accusation, constant request for scriptural authority and a calm spirit work miracles.
You are dealing with T-Rex mentality. They detect movement and you are breakfast! You can't look like you are moving away from dead center.
Personally, I think I was D'F'd illegally. There were no accusations and no witnesses to an offense in my case. I didn't even know I was at a disfellowshipping meeting!! I thought I was being asked about my separation from my wife and the reasons behind it. (Alcoholism).
So, I answered too many questions and asked for no verifications and played into their hands. I was stunned that I was disfellowshipped.
If I had it all to do over again I do it differently. I had faded and was no longer attending meetings. When my overseer called me on the phone to come "talk to the brothers" at the hall I SHOULD HAVE decline kindly. But, nooooo. I went. Bad move.