It all comes down to the individual player. The same rules that apply to Cedric Benson didn't apply to LT and don't apply to Frank Gore. Don't let a player's age get in the way of seeing their value.
2. You don't want to pick a receiver from a team with lots of good receiving targets
The elite quarterbacks of the league have the capacity to support multiple top receiving threats. But people, myself included, are often wary of taking a Jordy Nelson or Roddy White because Randall Cobb or Julio Jones is going to take too many targets away.
Last year it was either a Roddy White game or a Julio Jones game, it seemed like every other week you'd get burned if either guy was your top pass catcher. So the question often becomes: should I take the top receiver in an inferior situation or the first/second/third receiver with a great QB but more receiving options.
Larry Fitzgerald or Roddy White? Dwayne Bowe or Jordy Nelson?
There are so many examples and counterexamples that it is very difficult to make a hard-and-fast rule about crowded receiving corps. Last year, Aaron Rodgers had only one receiver with at least 900 yards (Randall Cobb finished with 954) while Tony Romo and Matt Ryan each had three pass catchers go over the 900 yard mark. The previous year, both Jordy Nelson and Greg Jennings had nice fantasy years.
Like in the first section, it is difficult to find validity in any broad generalization. Sometimes crowded receivng corps with good quarterbacks produce multiple fantasy studs (Gronk/Welker, Jones/White/Gonzalez, Bryant/Austin/Witten, Colston/Graham/Moore) and sometimes they don't (Green Bay, Pittsburgh).
So, when in doubt, I kind of stick to this rule. Given the choice between A.J. Green or Brandon Marshall and Dez Bryant or Julio Jones, I'll take the guys who don't have a proven receiver playing next to them. But I think this is a psychological crutch as much as anything else. I don't want to sit around all week worrying that my guy isn't going to be involved on Sunday.
Secondly, consistency is key in fantasy. I prefer to have my late round flyers or waiver pick upsbe my high-upside guys. In the early rounds, when I'm picking players that are going to start week 1, I want to be able to pencil in 10-12 points. I'd love the upside of a Julio Jones or Randall Cobb, but I'll gladly take the targets and looks that I know Reggie Wayne or Dwayne Bowe, or even Stevie Johnson, are going to get.