My one piece of advice would be - once you are at a regional airline/charter company/etc - to take advantage of any and all possibilities to work as an instructor, check airman, safety officer, etc. regardless of whether the monetary rewards seem worth it for the work involved. I had opportunities to do this at my previous "career airline" (now defunct) and I turned them down - once I unexpectedly found myself in the job market again, I really regretted not doing it. That stuff really sets your resume apart from hoards of others.