While imbuing and infusing gems can be useful to raise your stats, many decisions come down to a personal preference.
Here are a few of my most successful combinations, with possible alternatives in italics:

• Strength - to lower roundtime and hit harder
• Wisdom - to enlarge your mind for longer hunts
• Intelligence - to quicken your mind for less time between hunts
• Coordination - for handy tasks such as cutting gems

The only way I've been able to make two imbues add to the same stat is by using a "+1" after a "+2 or more"

Here is a list of useful imbues:

abalone bloodtoken: +3 str
egg bloodtoken: +1 str +2 stam

bark bloodtoken: +5 attack rating
bloodstone fetish: +health -mana

wood bloodtoken: +1 str +2 agil
turquoise charm: +1 agi +2 coor

coral icon: +5 wis -2 intel
deadwood idol: +2 wis +1 stam

skullgem fetish: +5 intelligence +2 wisdom -5 stamina

moonstone charm: +1 wis +1 intel +1 coor