Preparing to Invest in Real Estate

[Lake Bradford]

Hi, I am 21 and a year away from graduating college and I plan on investing in real estate as soon as I graduate. I have been reading a lot of the articles on BiggerPockets about how real estate investing works, but I would also like to hear from the community as well. I already have a job lined up that pays around $140k annually and I would have around $20,000 to $30,000 saved up by the time I start working. I could also work from San Francisco, Dallas, Georgia, Boston, or Seattle. Which strategy should I focus on and which city do y'all think would allow for the most profitable investment? 

Thank y'all!