Just went through this last year. Took me two FSDOs and an IA to get a coherent story, since my experience was nonstandard and not easily quantified.
I would not be granted an appointment without a pre-vetting done via Email. They wanted me to tape out my experience vs. the Far Part 147 sections B, C, and D. This is the curriculum requirement for an A&P school.
My "approving IA" and I went through each line item, and guesstimated hours spent in each, then added types of work I had performed which met the subject area. We had about 80% coverage, but my time was HEAVY in maybe 10 or 20 of the few hundred categories. I typed everything up into a nice word document, added my IA's "introduction letter" and attestation that the hours and coverage areas were under his supervision. Signed it and emailed it off for blessing.
Once blessed, I made the appointment. Then the morning of that appointment, a second ASI reviewed my letter and documents and asked how I was proving exactly 4,800 hours of experience. I said it was totalled up in the FAR 147 tape-out, but that wasn't good enough for him. Meeting cancelled. His morning freed up at the expense of my two weeks. Fine.
I took it to a different FSDO, made a new appointment on the strength of the first blessing, then I went back 12 years and printed every damned work order I had ever had an eyelash's involvement in. It filled a milk crate. I used every sheet of a costco jumbo ream of paper and an entire toner cartridge. I tabbed it, sectioned it off by N#, and reviewed them to re-familiarize myself with some of the major works I was involved with.
I marched that into my 7:30am appointment and you could see the fear in the ASI's eyes when he saw my giant crate. He ssaid "someone has already approved these, so here ya go". Signed the form, I was out in two minutes. Two months of prep and anguish and documentation for 2 minutes of the third ASI's time.
I think "dealing with the FAA" should be Appendix E in part 147. It's a major part of the game.
I don't know if my technique would work in light of the new changes. I haven't reviewed them.