Over the several years that I've been part of the forum, I've read may threads recently by individuals who came out to their SO and had very unhappy results. Sometimes, they felt that their wife or GF was initially accepting, then changed unexpectedly.
I've observed a few things that seem to be a few common "mistakes" made by indvidiudals when they first come out:
1) Not telling enough - as in saying : "honey, I like wearing womens clothes" - and nothing more
2) Telling too much in that first conversation, perhaps while in the grips of the dreaded pink fog.
3) Its all about "me". Thinking only of themselves and their feelings, without giving any thought to what their SO might be feeling.
4) Lack of preparation - this might include not getting to know your SO, not thinking about what you're going to say or what questions she might ask.
5) Timing - there are good times to talk and not so good times to talk. Christmas eve might not be one of those times.
Anyone else like to suggest a few coming out errors.