Most of the Moe Traits aren't particularly valuable, but a few can really aid your survivability. Helpful Moe Traits include ones that regenerate HP or SP.
The full list of Moe Traits can be found here.
The key to success is picking the best party for the situation you're facing.
Each monster girl can typically assume one of several roles from the costumes she has (healer, tank, mage, warrior).
While some characters are better than others, you can still find success with just about any character, as long as you are equipping them with good gear and matching your offensive elements up with the weaknesses of the monsters in the area.
It's advisable to have at least one character in your party capable of healing and preferably has at least two of the following skills: Recovery, Party Healing, and Resurrection.
Zenox is capable of healing and resurrecting with items, but that can get expensive. You'll find it easier and cheaper to have a dedicated monster girl for healing.
Early game, you won't have a lot of options for party members. However, as the game progresses, you'll quickly have a large number of monster girls available.
It can be confusing to know who to play with at first, so look at the following traits when selecting party members:
The row a monster girl is in affects both the physical damage she deals and the physical damage she receives.
Standing in the front row ensures physical attacks deal full damage to enemies, but characters in the front row also take full damage from physical attacks performed by enemies.
Monster girls in the rear row deal half damage with physical attacks but they also only take half damage from enemy physical attacks.
There must always be at least one monster girl in the front row.
The optimal strategy is to place monster girls that use physical attacks in the front row and your monster girls who use magic attacks in the rear row.
Row can be set in the "Party" menu outside of combat by selecting the appropriate monster girl and pressing the R button.
Characters in the middle party slot are targeted the most, followed by characters in the slots next to the middle slot. The outside slots are targeted the least.
The optimal defensive alignment is to put your characters with the highest defense in the middle slots and the lowest defense in the outside slots.
To determine who has the highest defense, add the DEF and MDF values of each party member. A character with 75 DEF and 75 MDF has a higher overall defense (150) than a character with 100 DEF and 25 MDF (125).
You can also assign two companions to each party member, one attack role and one support role. Doing so will provide additional bonuses.
Assigning a companion to a party member will build their respective friendship levels. At friendship level 3, two monster girls can become roommates. At friendship level 5, two monster girls can perform a Double Scratch which provides each girl with a unique crown (head accessory) as a reward.