Once the interview is over, however, there is still work to be done.
Send a follow up
My opinion is that sending a letter or personal note is the best follow up. For the most part, calling is rife with potential pitfalls—wondering if you should leave a message, leaving an awkward message, or even getting into a conversation that undermines your successful interview. I think a handwritten note is the best way to go.
Your note should be brief and to the point—expressing that you are very interested in the position and you think you are a good fit. This note should have a much different feel from your opening cover letter that you sent.
Talk about how your enjoyed meeting with them and talking about _____. Talk about why after meeting them, you think you would fit in well at their firm. If you can remember a specific thing you talked about that adds a personal touch, put it in there. For example, if you are a comic book nerd and your interviewer loves comics, say something like “it is always great to meet another lover of all things Marvel.”
At the end of your note, indicate that if they need any additional materials to please contact you. Avoid the urge to ask them to respond and let you know when they will be making a decision.
Touch base with your references
If your interview went well, get in touch with your references and let them know to expect a call from the firm. They should already be on notice, but it is a helpful reminder.
If you noticed your interviewer keying in on certain topics, you can also ask your references to try and talk about those things. In addition, if you are really excited about the position, it does not hurt to tell that to your references.
If you were not given a timeline for when the firm will make a decision, be patient. Calling the next week to check in is probably overkill. On the other hand, waiting two months to follow up is not good either.
If you were given a timeline, stick to it, and give it some leeway. If the deadline comes and goes and you have not heard anything for a week, go ahead and check in—indicating you are still very interested in the position.