The first half of comments were all about personality, socializing, and tricks. Above all you need to be trustworthy. If someone asks you about X and you have a rough idea, tell them you think zzz, but you would need to look into it since it has been a while or you aren't sure or whatever. Make sure you DO look into it and follow up, especially if you find out you were wrong. If I hear you say something in a factual tone, I need to trust it as if I had done the validation myself or it is useless. Did you run tests, validate your numbers with a good scientific method, etc? If you are repeating something you read on a blog, don't repeat it as fact until you are sure of it. One slip up where your facts get iffy and I suddenly won't trust anything you say for a long time and will re-validate myself until you start telling me your facts and your methods in the same breath.