There are two other ways to generate skill points aside from the normal energy regeneration. Every time you complete a new mastery level of one of the jobs, you are awarded a new skill point. You can also go to (the Godfather) to purchase 4 skill points for reward points. This is probably one of the best uses of reward points.

When looking to maximize your gain of the skill points from job mastery, there are two things to consider: Different jobs complete at different rates and cost different amounts of energy.

So "Ransom a Business Man's Kid" costs 54 energy to do, but will provide 10% job mastery per attempt. "Steal an Arms Shipment" costs 40 energy to perform, but it only advances 6% job mastery per attempt.

All and all, this means it is 540 energy to unlock a skill point with the first job, and even though the second job takes 14 energy less per attempt, it is 680 total energy to master and get a new skill point.

Since there’s a need to master all the jobs in a given category at a level to unlock the next mastery level, it won't matter too much what order you do them in. A good rule of thumb is just to work from the lowest level jobs up to the highest and do the jobs that take the most energy per attempt first.