Not sure what the problem is with so many people.
I finished both of mine recently and there's no wizardry to it. i go to a set of never visited systems, preferably with easily reachable High Tech affiliated with the major faction you want to increase your rank in. Do all trade and fetch missions for all minor faction affiliated with the major you are grinding in the area, move on to a new patch after the high payout missions start to be offered as your progress will start to decline after that.
After 2 sets of systems I got my rank up, rinse and repeat.
I finished both of mine recently and there's no wizardry to it. i go to a set of never visited systems, preferably with easily reachable High Tech affiliated with the major faction you want to increase your rank in. Do all trade and fetch missions for all minor faction affiliated with the major you are grinding in the area, move on to a new patch after the high payout missions start to be offered as your progress will start to decline after that.
After 2 sets of systems I got my rank up, rinse and repeat.