There are indeed an awful lot of licenses available, but my advice is to go for balance. Don't waste all of a character's points on just weapons, or armour, or spells; but try to get a few of each now and then. If a character's good with magicks and has some spells already, then maybe they can focus on magic and magic power more than on getting better weapons. A bit of specialisation can be helpful. For a naturally strong fighter, you might want to get a few more Augments - the licenses that boost HP, attack power, and the like.

As for gambits... since you have so few gambit slots to start with, try for something simple like setting their first gambit to "ally - any > phoenix down", so they'll automatically revive a fallen foe, and "foe - party leader's target > attack", so they'll automatically gang up on whoever you want to attack. Healing gambits should always take top priority, i.e. they should be higher on the list.

To be honest, the gambits aren't much help in the early hours of the game. It's not until you get more characters and more gambit slots that it really starts becoming helpful.