I know this is one of those fairly polarized topics but it seems like more and more people want to get a digital version of the photos, some want the full res versions obviously for their own printing while others are fine with lower res for social media.
You give up the files, you better make a lot of money for it.
Another issue is a client misrepresenting themselves and intending to use your photographs for commercial purposes but posing as an individual.
When someone pays for files, you give them the release. And you dictate the terms of the release. Personal use only, no corporate use. If they use it for corporate use, then they are in violation of the licensing agreement and they are on the hook for a copyright violation (actual damages plus attorney's fees plus up to $150k because you were smart enough to register them within 90 days of first publication.)
So if someone misrepresents them self, they could be in for a huge legal problem.
For those who give out full res files, do you have the client sign a release granting them reproduction rights only for personal, non-commercial use? Do you give them a formal release at all?
If you don't you are stupid. If you are giving them use of the files, you need to specifically give them a document outlining the agreed upon usage.
How much profit is there in the printing part as opposed to charging a set fee for the shoot and the disc with retouching an additional charge?
It all depends what you are doing. But if you are a portrait shooter (babies, seniors, families, etc) then roughly ALL your profit comes from prints. Giving the disc away is a great way to go broke immediately.