Strive to help people. It is the right thing to do, and people are keenly aware of who have in the past given them or theirs favors. If you ever can’t help someone but know someone who can, pass them to the appropriate person with a recommendation. If you do this right, two people will be happy with you and favoritably disposed to helping you out in the future.
Also: communication is a very important professional skill. It's a long read (as far as the Internet is concerned), but worth it.