I like identifying 3-5 positions of need and pick the BPA available who fills one of them. For example this year I'd rank it something like:
1.) Cornerback
2.) OLB
3.) Outside Wide Receiver
4.) Safety (depending on Burnett)
5.) Right tackle
6.) Tight End
Then have it on a somewhat weighted scale, so if there is an amazing Right tackle or Tight end you take him but if all grades similar go with the position of more need (CB/OLB). If there is a quarterback, running back, or some other position you absolutely don't need then consider a trade back to ransom the pick to a team who does.
As for this year...
I think there are some real talented players like Derwin James, Roquan Smith, and Tremaine Edmund who don't necessarily fill a primary need but they may not be able to pass on if they're still around. However I'm guessing they are off the board and the Packers settle for a safer pick like Josh Jackson, Marcus Davenport, or Harold Landry. Safer meaning they fill a main need they have and are more likely to still be available.
If the Packers trade back (or trade up from the 2nd round) I really like Vander Esch from Boise St, he reminds me of a young Clay Mathews and the Packers certainly had no problem making a move for him.