I've been an attending now for 3 months, and chose to do locums at different hospitals to get some more exposure to different practice settings.
Here's my advice/experience from being the "very" new guy at three different hospitals so far.
1) Go by the book. An attending told me that in his first six months as an attending he had about half a dozen complications, and all of them were from making a decision to "push the envelope" a bit. He told me to simply not do anything daring, keep it simple and straightforward when you just start out. I did just that and highly recommend it. Your life is going to change a lot in the first few weeks, adjusting to a different practice setting, different equipment, different drugs, different procedures. Keep one thing consistent, the way you practice.
2) Don't assume anything about the surgeons. When you get a list of patients for the next day, talk to the other attendings and the nurses. Ask how long they generally take, and how good they generally are. I just did a TVH, which always took 2-3 hours where I trained, and this guy was done, skin to skin, in 30 minutes. You look stupid if you're waiting half an hour for the patient to wake up because you assumed wrong.
3) Get three phone numbers. You're on your own, even though there's lots of other attendings around you, you won't know them as well and may be more reluctant to ask questions and advice straight off. Set up three friends who you trust clinically so you can call each other, night or day, set it up so you've got a good support network that you can bounce ideas off of. A buddy of mine, who's been an attending now for two years, just sent me a text asking for key things to keep in mind for mandibular resections. BAM, a quick refresher and he's rocking! I just did a cardiac case, called a buddy the night before to make sure I still was thinking about it the right way. Gives you a lot more confidence and cuts out a lot of stress.
4) Live like a resident for a while. I know a lot of friends that spent half their first year's salary before they even had it. You've been living on a much smaller budget for a while, slowly ease into your new circle of wealth, it'll leave you a lot more financially sound and less stressed about your billing.