Here's some other tips for good improv.
1. Don't perform, just have fun. Embrace the moment in play rather than trying to control the outcome. When you aren't performing, you are less self conscious. When you're less self conscious, you are more responsive to people and they are more responsive to you.
2. Embrace failure. When improvisers are just starting out, they are taught to take 'failure bows' everytime they get that "oh crap I screwed up" feeling. The rest of the performers clap and cheer. The beginners are actually encouraged to have at least one 'failure bow' per class. When we aren't so afraid of failing, we take setback with more grace and are able to move forward more quickly.
3. Say "yes, and" not "yes, but". This goes to what my friend learned, build on what other improvisers have given you. "Yes, and" creates better conversations by validating what someone else has said and branching out with something new. Apply this concept to life in general: Say "yes, and" to life and accept what it has given you, good and bad, and take that and build on it. Saying "yes, and" implies an acceptance of reality and a willingness to move forward and take the next step.
If you're brave, you can use these ideas anywhere in your life. I'm currently pledging to use them at work. I will play when I'm teaching, take a 'failure bow' when I need to, and encourage positive interactions with my coworkers by striving to say "yes, and". And maybe, just maybe, this improvisation will spill over into the rest of my life.