I was browsing through AAEM's Commonsense Journal (Sept/Oct 2012 Issue PDF) last week and came across a brilliant article by Dr. Andy Walker. He is a mentor for young EM physicians and offers these points of advice:
Live beneath your means. Save 15-20% of income if you are employed. Save 25-30% if you are an independent contractor. Stay out of debt and pay off debt as quickly as possible. EPs should have at least 6 months of income saved, as ER jobs are inherently unstable. Money may not buy happiness, but it does buy freedom - and freedom is pretty damn good. Save your money.
Rent, don't own. There will be surprises and you will be in a stronger position if you can pick up and leave. Especially, rent for the first year.
Insure wisely. You absolutely need disability insurance, as you are far more likely to become disabled than to die early. Get "own occupation" disability insurance. If you do get life insurance, get term insurance.
Be a faithful and disciplined investor. Start investing early and time will be on your side. Diversify widely. Educate yourself. He recommends books by John Bogle, the founder of Vanguard.
Participate in organized medicine. The biggest enemy of physicians is their own sense of hopelessness. But a difficult fight is not an impossible fight. Join your state medical society. Join AAEM today.
I'd also like to add a couple of things:
Be happy now. You have arrived. Stop getting trapped in thinking, "I'll be happier, once I get the BMW, house, etc."
Seek balance. Residency can be extreme and now is the time to focus on your health, family, friends, fun, leisure.