Just a word of advice, the fewer people who guess correctly, the fewer cards are produced for that month. I would imagine that a ton of people are going to guess on players today and tomorrow since its opening day. So, even if you choose correctly, there are going to be a lot of that player's cards produced. I'd recommend choosing players on days where you think fewer people will pick him.
As for the actual picks, I'd look at the player vs pitcher matchups. If there's any good ones favorable to the hitter, let 'er rip!
#COMMONCARDSMATTER
"The 0-2 pitch... SWING AND A MISS! Struck him out! The Philadelphia Phillies are 2008 World Champions of baseball!"
- RIP Harry Kalas