You earn coins every day you log in. You use those coins to buy virtual packs.
You "play" up to 9 cards at a time, and based on each players performance, you earn or lose points.
There are common (white,) uncommon (green,) rare (red,) scarce (silver) and super rare (gold) variations. Think of everything above common as a multiplier. Uncommon earns more than common, rare more than uncommon and so on.
Right now, starting pitchers are where it's at. They can earn you a ton of points if they have a good game, They can also lose points, so choose wisely.
What I like to do is when I get up in the morning before work, I use mlb.com 's schedule for the day, and select pitchers and hitters based on that.
I will play as many players as I can for a specific time period. For example, if there are a couple of 1pm games, I will fill my line up with players from those games. Then, I will do the same for 4-5pm games, again at 7pm, and 10pm (EST.)
You can get even more detailed if you want to..like for example, if you choose a starter, and he is getting killed, you can remove him at any time. You will still score, or lose points for the time he is in your line up, but you can replace him with a reliever, hitter, whatever you choose. Sometimes, is makes more sense to remove a starting pitcher and replace them with a batter if that batter is having a great game. Just remember you only score (or lose) points for the time they are in your line up. If a pitcher starts off bad and has a couple rough innings and you choose to remove him, you stop receiving (or losing) points if he happens to straighten things out, unless you put him back in the game.
Hope that helps some!
How does this work with retired players?