LIFO and FIFO are practices in accounting for managing inventory. "LIFO" stands for "Last in, first out." I'll let you take a wild guess at "FIFO."
When it comes to managing your inventory of assets on your fantasy roster you may start with a LIFO policy, but it shouldn't stay that way. It is likely that after your draft the most vulnerable player on your roster will be the guy you picked last or that $1 auction buy at the very end.
Inevitably there is a new closer (like Alfredo Aceves just yesterday) or some other hot player that you will want to add to your roster. If the games haven't been played yet and you are just dealing with injuries, you may in fact be dealing with a LIFO situation.
As the season evolves, you'll have to take a more critical eye. Pay attention to the rising and falling values of not just available players on the waiver wire, but also your own players. And, listen, everyone gets attached to their own stuff in life... it's human nature. But you, you've got to find a way to rise above and fairly evaluate the players on your own roster. Don't think more highly of them because you own them. Maybe you are a super genius and your players reflect that, but you will look like more of a super genius by making preemptive genius moves on your waiver wire.
The most critical point here is that sometimes how swiftly you can execute a free agent move is of utmost importance. If you have a rolling free agent process where free agents are immediately available once they clear waivers you'll need to be quick to grab guys when you hear good news about them. So, listen up, this may sound like a small thing... but you always have to know: Who is the first player to go? Who is ranked the lowest? Who has the longest value to your team as an asset? You may pick one pitcher and one hitter in baseball, but the bottom line is that you have to know who the weakest link is.
This will free you up to execute those free agent pickups quickly.
One last thought on this, my friends. When you start to think of one player on your roster as the weakest link the opposite of the "we all over-value our own stuff" rule can start to take root. You can start to think of that one player as junk that you are ready to throw away. Maybe he is, but you put him on your roster in the first place for a reason. The object here is to upgrade that slot, not just throw away an asset.
Best of luck with your free agent acquisitions this year. I'm sure we'll talk about FAAB in this space soon... so be on the lookout for that.