Well, hello!
If I may share my preferences in Cards:
Reds
Centaurus: I’m using/testing Centaurus (3x) at the moment. They’re fine, I like the extra AoE.
Glass Mole: I haven’t tested it yet, but pretty sure Glass Mole is a nice choice, more damage for something you would be doing anyway (using SP potions).
Blues
Zaura: Physical Def is always useful. Don’t be afraid to go with it. (1~)
Nuaele: Magic Def is also always useful. Just balance if you need more physical or more magical defense. (1~)
Greens
Blut: I personally really like CON. I still don’t have my greens, but Blut will be my choice.
Netherbovine: STR. Again, can’t go wrong with more damage.
Card that gives both CON and STR: I don’t know the name of it, but I would be nice, maybe.
Purples
Gazing Golem: I LOVE it. Just one Gazing Golem is so helpful, I couldn’t believe it when I started using it. Procs Pain Barrier all the time and for a good amount of time.
Marnox: I’m using Marnox (2x) for some extra yellow numbers, not a ton, but Crit Rate is always welcome too.
Rikaus: Haven’t tested it, but some say it is nice in faming situations, 'cause SP potions and Cannon-Matross are SP hungry.
There is a Guide about Cards, it may be helpful if you want to know more: Card Guide by Miguelmiamp
Now, onto Gems:
As none of this classes have skill gems, the gem situation is kinda simple.
Weapon: Go for Red Gems.
Shoes and Gloves: All the others are kinda weird besides the Green Gems for me.
Top and Bottom: Go for Yellow Gems OR Blue Gems, depending on what kind of defense you’re feeling you need.
Hope it helps!