Benjamins while brandishing a sidearm. Or just take your posse along with you.

Actually meeting at the bank is a good idea. If you use same bank then perfect. Otherwise possibly an interbank transfer?

I've only bought one and seller requested 20's. I had multiple phone calls to make sure everything was legit before I made arrangements I did take a risk, but given nice part of town I did feel safe. Also was very observant and drove around house before actually pulled in. Left money locked in car, and felt okay once in house and met guy with toddler their (although this could have been to make me feel safe). Was late afternoon, so plenty of light. I think you should always be careful when exchanging cash with strangers, and whatever you can do to mitigate risk is worth it even if it cost you something in money and convenience.