Pick your five best Pedroia autos or game used and then go slow on the vintage cards of iconic players. Second or third year cards of some players will be fairly inexpensive in collector grade so if you have a decent budget you can pick up 2 or 3 cards a year depending on what you decide on and who the player is. Even cards from 10+ years for certain players in PSA 6 or 7 are fairly affordable as well.
I PC Willie Mays and you can pick up some nice 60's PSA 7s for anywhere from $100 to $250 depending on the year. The same goes for Hank Aarons cards as well. You can also choose cards that have multiple Hall of Famers on them like the 60's league leader cards in high grade that have great combos like Mays and Aaron, Clemente, etc. If you have set goals it will be fun if you pick up at least a new card every month. I find if I do not pick up at least that one then I lose focus and start buying modern wax or single card autos on ebay that do not fit my PC.
The Red Sox have some really good players and HoFers and you can easily afford some of those cards in high grade from the 70's 80's and 90's. As long as you keep it fun and don't stray too far off task your collection will form right before your eyes in a few years. Good luck!
Baseball: Collecting Mays, McCovey, Cepeda, Marichal, Perry, Posey, Clark and any other SF Giants players. Football: Modern autos