what to prepare for?
 

Im a CFI with 500/36. I want to fly 121. I want to start preparing for the airlines but what/how should i prepare? How long should i wait before applying? Would it be worth it for me to get my MEI just to bump te multi hours or is it a waste of money, because the regionals will hire my anyway?

Thank you!

500/36 you seem way overqualified.................

The regionals are hiring low time guys but unless you have some turbine time or know somebody on the inside at TSA or PSA, you will probably need more than 36 hours of multi. I highly suggest the "turbine pilot's flight manaul." Its an awesome overview of many systems CFIs never learn about.

Also "Everything Explained for the Professional Pilot" This is a great book.
121 regs, Duty Time, Alternate Minimums and more are explained.

I agree completely with the 2 books already suggested. Also, I'm glad my company required the ATP written. Just studying for that helped me lots for the technical interview questions I was asked.