Here's the important rule of making twin ocs:

TWINS ≠ CLONES

Twins are people who are biologically the same, but it doesn't mean they're the same person. Twins have a mind of their own, liking or disliking some things.

Clones however, wear and do the same things. There is nothing unique about them and they are just bland.

Make your twins have a chemistry, a Ying with a Yang. One twin is creative and expressive, the other one is average and you don't expect much.

It's ok if the twins like the same things, as long as they enjoy different categories of it. Like two twins enjoy making music, one makes the lyrics and the other sings it.

What are their relationships? Do they love each other? Or do they have against each other?

Twins have to have their ups and downs in their personalities.

Use Marsie and Ari for an example: Marsie is quick and agile, but she doesn't know when to stop and gets carried away easily. Ari is smart and untouchable, but can't stand without someone behind him.

Twins designs also have to be similar (unless if they're fraternal twins) but fraternal twins still have to have details showing that they're related.

Also, this isn't really needed but the names should either rhyme or match in a way.

Ex:

Kyle and Lyle
Via and Mia
Dana and Pearl
Kalla and Viem

Welp, another quickly updated chapter by the one and only Debs. I'm actually running out of suggestions sooo tell me what you need help with!