Rule Of 20
Marty Bergen devised this guide for opening weak hands (less than 13 HCPs) in first or second seats:
Start with your HCP total and add the length of your two longest suits.
If the total is 20 or more, open. If it is less than 20, pass.
Most of your HCPs should be in your two longest suits. Widely scattered honors or unprotected honors should be downgraded.
KJ764 8 Q54 AJ62 -- Open
In BidBase, we require the two long suits to have at least 8 HCPs between them. We also specify 12+ KNR points, which discounts honors in short suits.