One popular method of hand valuation for the purposes of Opening the Auction is called The Rule of Twenty.

If the sum of HighCardPoints + length of longest suit + length of second longest suit = 20 or more, The Rule of Twenty suggest opening.

Here are some sample minimum openers that you might previously have previously been passing with, but now might consider opening:
Axxx xx x AQxxxx
AQxx xx xx AJxxx
Kxx KJxx KJxxx x
QJTxx QJx KQxx x (yuck)

If you don't routinely open these hands, consult with partner before accepting The Rule of Twenty as an opening guideline.

In fourth seat The Casino Count is often a preferred alternative: If Number of Spades + HighCardPoints >14, open. Otherwise PASS.