I'm also in the camp of favoring both index funds and real estate. My strategy is to put taxable funds toward RE downpayments, and keep retirement funds in index funds to diversify across both these classes. This way my taxable funds are placed in the best tax shelter available, and index funds that are normally tax inefficient (bonds and REITs) are also in tax shelters. I understand some folks like the idea of putting retirement funds into real estate, but I've also read and agree that it doesn't make sense to put a tax shelter inside another tax shelter, given that you can't take depreciation tax deductions or use mortgage leverage with retirement funds, reducing your retirement returns.
Since you are looking to spend only $20k-$30k on your first rental and possibly do it out of state in a more affordable market, you may want to consider investing through a turn-key company in markets like Memphis, Indianapolis, Kansas City, Cleveland, Dallas, Houston, Birmingham, or Jacksonville, FL. They acquire, completely rehab, screen and place tenants, then sell you a finished package, then manage it for you afterwards - in effect a one-stop shop to make it as passive for you as possible, since they want to keep you as a repeat client. True, they do sell you the property at or just below market rate, but for busy full time w-2 career folks, it can be worth it to avoid having to vet and then coordinate the realtor, RE attorneys, title companies, contractors, inspectors, and property managers. $20k-$30k can act as the downpayment on a $90k-$130k property, which generally attracts higher quality tenants, hence fewer problems and higher returns. Also cashflows around $200-$300/month.