I joined yesterday and I'm confused about some things. I hope it's alright if I ask because I searched around and couldn't find answers.

1.) How do I get trait points?

2.) Can I add genes to a sylesti that's already been generated?

3.) Is it difficult to sell pets you've bred? Since there aren't player stores...

1.)Trait points aren't really obtainable, you get them by breeding pets, and it operates of of simple Genetics.
Here is a link to the Breeding Guide:
https://www.sylestia.com/forums/?thread=370

2.)Generated no, But you can mutate Tamed pets. For example...
+=
It wont always have that gene and will be a random selection of either carried or visible gene or mutation. however sometimes you can obtain philters that let you chose.

3.)It depends on the pets you are breeding, Many players do project based pets that ar trying to reach a spicific goal so for example I have Sweetheart Puffadores.

If people like the design the pets are easier to sell and for better prices than just random tamed pairings.

I hope that helps! and welcome to the community! we all love to help out so if you have any more questions feel free to ask ^-^

to 1/2, adding to what has already been said
Genetic Mutators:
Lesser Genetic Mutators: will add one random trait in an open slot (no vis, no carry), and it may be either visible or carried.
Greater Genetic Mutators: will allow you to choose one trait to put into an open slot.
Lovely Mutator: Only available during the Week of Love. Allows the addition of either Valentines Lace gene (all species) or Lovely Hearts mutation (only some species) if the respective slot is open.
Lucky Mutator: Only available during the Fortune Festival. Allows the addition of either Lucky Runes gene (most species) or Lucky Dust mutation (all species) if the respective slot is open.

- You can only use one mutator on a pet
- The pet must be Tamed

Okay, thanks :)

So there's absolutely no way I can add anything to this girl

Lol I want those sweetheart puffs now XD

I'll gladly breed one fore you, they are 5,000 g if that's okay

I only have 3,615...

Well they will always be here, no rush But your first on the list so don't worry i'll save you one!