This is a friendly reminder that when you tune to approach frequency with the intent to request an approach or vectors, you do not need to check in. Simply request your desired approach. On a busy frequency, this can really clog up the frequency, because we have to respond to both the check-in and the request.
On the other hand, don’t switch to approach frequency after departing unless tower explicitly tells you to contact approach. Then, if tower tells you to contact approach, you will check in. If you’re flying IFR, you do not need to request flight following, a check in is enough. If tower does not instruct you to contact approach, you do not need to contact approach.