Is this your G&L? I believe those have a two-way truss rod, but either way the same rule applies:
If the neck is too concave (action too high), turn the truss rod nut clockwise to remove excess relief.
If the neck is too convex (strings too close to the fingerboard), turn the truss rod nut counter-clockwise
It's always best to check intonation after. It may be fine, or it may need a tweak. It's not a huge task if it does need adjustment (unless you have a Floyd Rose).