Go read white coat investor. It has all kinds of good information.
I would NEVER recommend investing in anything but real estate, mutual funds, and your own business. I know a bunch of doctors who lost most of their money investing in things that they don't know about (their friends businesses, subway franchises, etc, etc)
I am actually selling all my stocks and going to buy condos in certain places that I think will improve more than other places. I grew up in LA and am willing to make a 20 year investment. I plan on moving into each condo for 6 months to get the good mortgage rate and then renting them out forever.
Since I became an attending I have been living at 50% of my salary. I purchased a home 2.5 years ago that was about 1/3rd of what I could get a mortgage for. I've saved the rest. When you go from a resident to an Attending, for a little while don't change your lifestyle.