When I started to get serious about drawing this winter, and I was able to produce a few decent-looking portraits, I gave a standing offer to a group of friends to draw portraits of them or their kids for free; I'd mail them the original if they'd pay the postage. This was a good way to get a bunch of good source images, and also I told myself it was better that someone would hang up and enjoy the drawings rather then have them stored somewhere in my house.
So I therefore gave away a whole bunch of drawings I really liked, and each one hurt more than the last to part with! This was only slightly mitigated by the thought that people would be enjoying my art in their homes. This one was the last one I gave away -- after this one, I couldn't do it anymore:

So I started drawing celebrities and my own family members! Now if someone wants a drawing from me, it's either a gift, or they're going to have to pay for it