I have a cold. should i wait till i get better to take the ppd shot/tuberculosis shot?

Doesn't matter: One can get a PPD skin test regardless of whether or not she has a cold. Regarding TB testing, sometimes getting a Quantiferon TB blood test is more accurate or more desirable than a PPD skin test (one's primary care doctor can advise on that). For example, a person who has had a BCG shot and has not had a negative PPD test since the BCG shot, might want to do the blood test instead of a PPD test.