Oh my. I am so sorry. I started a thread and then had a frenetic week and didn't check back! And there are a ton of thoughtful replies. I'm now resurrecting this thread off of page 5, ack. So I will reply in general rather than individually, if that's ok, since I have to dash off to a soccer game soon.
Glad to hear I'm not the only one who had mixed success with new colours! One thing I didn't know: that you can return a used colour the next day to the makeup counter. I think I'd feel bad doing this, though. They would have to throw it away. It's not like returning a sweater.
Many of you suggested improving lip colours by mixing them. Yes, I do this -- sometimes deliberately, and sometimes even by accident, because I put on lipstick in the morning and don't necessarily have the same colour in my pocket or handbag later that day!
Some people mentioned putting lip balm on to soften colour. I agree, it does. I always, always put on Vaseline before applying lipstick, or my lips dry out. I am a Vaseline junkie. It's more intractable addiction than heroin. However, I have discovered a number of formulations that stay on for longer and are much less drying than others. It can vary by colour, even within the same brand. Chanel makes some nice bright reds that go on smoothly; Estee Lauder has an excellent dark purple that doesn't clump (a common problem with dark shades); and Clinique Chubby Sticks Intense give almost as much colour as real lipstick, but seem to last longer.
Anyway, thanks so much for your helpful replies! Off to put on my lipstick now.