The AAMC recently posted a piece with tips on how to avoid delays in the AMCAS verification process. The link to the article is below, but I've created an outline of their recommendations here:
1) Submit all of your official transcripts – including college courses taken during high school. The AAMC notes that transcript issues are the most common cause of verification delays.
2) When completing your application, include alternate names that appear on your official transcripts so AMCAS verifiers can readily match your transcripts with your application.
3) While this is not a requirement, the AAMC recommends you use the Transcript Request Form (TRF) to match paper transcripts to your application. The TRF can be found in the application's Schools Attended section.
4) When requesting e-transcripts, ensure you provide your accurate AAMC ID and Transcript IDs to avoid problems matching your transcripts with your application.
5) Make sure to fill out your coursework exactly as it is printed on your official transcripts (including abbreviations, grades, and symbols) and in chronological order. Include all courses - even ones you took more than once, you withdrew from, and/or you did not excel in. The AAMC recommends you order a personal copy of your official transcript early so you can complete the coursework section accurately.
6) If you are reapplying, resubmit all of your transcripts and your letters of evaluation, even if nothing has changed since your last application.
7) Proofread your AMCAS(!), as there are limited changes you can make once your application is submitted.
Here is the AAMC article.