Doing girls' free-roam events will give you +1 permanent points (don't remember which events give which +1 points) each that will increase your stats.
Also, yes, grind until you get the best reward in terms of equipment.
For example with Nimble Fingers, iirc, the best reward is Lock Glasses which gives a pretty big boost in Knowledge & Intelligence stats when equipped.
Also, until you get the best equipment, it's good to make use of shops which may have good equipment that may give you a boost in stats.
Basically, it's a game of swapping in and out equipment (swap out your lesser equipment and swap in better equipment when you either buy or obtain them by reward).
Following are the current best equipment in the game (equipment's rarity in brackets) which I have equipped:
- Fedora (Rare)
- Long Coat (Rare)
- Bulletproof Vest (Rare)
- Hardened Gloves (Rare)
- Holy Pants (Epic)
- Lock Glasses (Legendary)
By the time you get all the above equipped to your MC, contracts will be easy-peasy when you go through repeats.