Welcome John to the BP Community!
Have you read Rich Dad, Poor Dad yet? If not, it's a great read & highly recommend it.
Boston is a tough market and you either need a lot of money to put down or a great job that provides you with high income or a combination of both. I don't want to sound like a downer, but a lot of these books and even conversations in BP don't apply to Boston. It's like trying to invest in Manhattan, the market has already been bought up and you need to find the surrounding areas that will be the next hot spot (think Brooklyn or Bronx NY). There are stories of people getting great affordable homes here, but they got them back in the 2007-2012 recession. You can't buy a home here in MA for really under $300k and if you look at some of the discussion groups, people are buying homes in NC, Georgia, Maryland, Ohio, & places where you can buy a MFH or SFH for really cheap ($150k - 250K). The rules they use don't really apply for Boston, but they can work outside of the city in other areas like; Haverhill, Lowell, Lawrence, Worcester, & Fall River. You can house hack and do the BRRR strategy in MA, it is tough to find and even harder to bid on & get one in Boston though. A lot of contractors & developers buy up all the MFH's and turn them into condos. Boston gets a lot of investors from all over the world and even covid hasn't seemed to slow that down. You can try close to the city like Everett, Revere, & Chelsea. Again, even in those areas, the homes are still pricey but you can find deals (around $550k - 600k).
First thing would be to talk to a bank / mortgage lender and find out what you can afford and what loan options you can get. Based on the loan amount & down payment, come up with a plan, research the areas you can afford and figure out what your goals are. Do you want a nicer 2 fam that you can live in almost rent free in a great neighborhood for a long time or do you want a 3-4 unit, cash flowing MF that might not be in the best area, a little further from Boston but you can move out of it quickly. You also don't have to go at it a lone. You could get a partner and see if you both can tackle your first investment together.
Stay positive & never give up, always keep pushing and moving forward. There is never a bad time to invest in real estate, people will always need a place to live. Biggest thing is, do your numbers. Always run the math & give yourself a cushion for decrease in monthly rent, vacancies, repairs...etc
Good Luck!