This build works by using the Hunter set buff and giving the Kavat as much ability to do damage as possible, therefore giving it more survivability and usefulness without losing too much utility.

As the smeeta is commonly bought with a [Nekros] slash build for farming, stacking the Hunter set which allows the Kavat to do more damage on Slash afflicted enemies is a useful build for farming.

Smeeta buff
[Charm] is the smeeta's default ability and what most people use it for.
[Tek Enhance] is used to make the buff last for longer.

Critical Chance
[Bite] increases the cat's own critical chance.
[Hunter Synergy] boosts the cat's critical chance with a sync to your primary weapon (can hit over 100% on the cat).

The smeeta innately has a decent crit chance (20%), so stacking this is useful (similar to any weapon).

Damage
Maul gives the cat extra damage.
Hunter Command or a 60/60 Mod ([Frost Jaw], [Shock Collar], [Flame Gland] and [Venom Teeth])

Survivability
Link Health gives the cat extra Health. Remember if you are on something like [Hildryn] then Link Shields may possibly work more to your favour. This mod works with "base" warframe modded health, not how much health you have each moment in combat.
[Primed Pack Leader] (or [Pack Leader]) allows your melee hits to heal the kavat.

Utility
[Fetch] lets the kavat loot for you.
[Primed Animal Instinct] (or [Animal Instinct]) allows the kavat to show you enemies and loot on the map.

Other mods
The dps mods ([Frost Jaw], [Shock Collar], [Flame Gland] and [Venom Teeth]) can be useful as well if you are thinking of bringing your cat for more dps over utility.
Use [Hunter Recovery] if you think you can manage it with the frame (something like [Inaros] is an idea), but it can suck your health if not careful.

Make sure you set up [Charm] in the first slot on the left, because it will then proc' most often.