Great initiative to come up with this topic. I always have a medkit on me. While healing someone isn't as glorious as the top fragger, it sure helps your time quite a bit.
One thing I would like to stress, is to provide cover while being healed.
1. Make sure you're behind (if possible) the person you heal, keep out of his/her Line of Fire.
2. Heal in turns. One providing cover, the other healing. I guess this is hard in a fast paced environment, but it works out in the end.
3. When playing in small groups near a bottleneck, fall back when you're low on health. Most medics will heal you immediately without requesting. (Personally, I tend to stick on the rare of these groups, heal people to compensate for my lousy shooting..
4. While being covered by the one you healed, you can easily do a weapon reload if needed.
Maybe it's a good idea to come up with a extensive list which contributes to the overall teamplay of the game?