When I ran the in-house studio at Time Warner Global Media, I had a scalable freelancer staff. These tips are from both my experience as a manager and while chatting about the gripes of PMs as a freelancer.
Be on time
Let them know that you are running late, traffic, train delays, its all part of the commuting adventure. Send the PM a text even if it’s just 15 minutes late, it lets them know that you care about being there for them.
Say good morning and good night. And let them know when you going to lunch, have to leave early or come in late. Especially if you sit right next to them!
But don’t bring in extra personal stuff, you never know if budgets run out unexpectedly.
Do not to change the settings or personal settings : i.e. (backgrounds) unless they directly affect your productivity. Managers don’t have time to go into the machines after every freelancer to undo what you just did.
Come prepared and bring your arsenal
Get a portable drive or use drop box (dropbox.com) and bring your bag of tricks (fonts, textures, backgrounds) just make sure that you have proper licenses or ask the client to buy their own license.
Stay on top of trends and program updates. Especially Key Commands!
Don’t check social network/email. Do it in your break, a lull or if you have to answer another client, just let them know.
If you need a break, ask for one. Sometimes you just need to refresh to do your best work. But don’t take long breaks without letting them know before hand.
Be considerate with your filing system
Make sure all your files are easy to use even when you are not there.
Be true to their filing system
Layers and files named and possibly color coded
Save your samples for yourself but ask for permission when doing so, especially if you want to post on your site.