When you've got an entire player pool from which to choose in daily fantasy football, there is no need to roster a player in a difficult matchup.
As such, I spend a majority of my research time in DFS looking at a team's opponent. If a great running back is facing a great defense, why would I use him when I can simply select one of his peers in a better situation?
A sweet tool for spotting plus matchups is numberFire's Net Expected Points (NEP). If you're new to the site, NEP is a measure of the efficiency of teams and players based on the expected points they add or subtract relative to expectation.
In every situation, there is an expected number of points a team will score on a drive. A positive play (such as a three-yard rush on 3rd and 2) will increase that. A negative play (such as a three-yard rush on 3rd and 4), will decrease that. Sum up each play throughout the year, and you've got yourself an NEP. Team NEP totals are adjusted based on strength of schedule.
So that I can more easily find positive matchups to exploit, I like to put them all into one spreadsheet. It's complete with colors and everything so I can look like I'm doing something way cooler than researching DFS when I'm in a coffee shop. I also include Vegas over/unders and lines so that I can see which offenses are the best to look at each week.
We'll have this spreadsheet up on numberFire each week in case you would want to integrate the info into your research, as well. It's not a "cheat sheet" because you'll still need to implement your own knowledge and strategies, but it can at least aid you in spotting offenses that will be in a good spot. A cheat sheet implies that you'll all be using similar thought processes when filling out your rosters, and that could not be further from the truth.