I think I've told you something similar already, but I'm still going to repeat myself. Sorry for that. I'm talking again about using logic or more like COMMON SENSE when creating characters. I'm going to write about two things I came across recently.

1.

I saw this one character quite recently. She was half Chinese and half Korean and she lived in States. Nothing bad yet but just wait. Her sister is SNSD's Taeyeon and SNSD's Tiffany and Jessica are apparently her cousins....

EXCUSE ME, WHAT?

First to say Taeyeon does have a younger sister but she definedly isn't half Chinese. And also Jessica Tiffany and Taeyeon are not related to each other in any way. And if Jessica is her cousin why isn't Krystal of F(x) her cousin? They are sisters! That's well-known! Tiffany and Jessica also have other siblings that should be mentioned as her cousins and Taeyeon has an older brother that should be mentioned is the OC is her younger sister. I've seen many similar cases and I just want to say:

IF YOU ARE GOING TO MAKE YOUR CHARACTER SOME ACTUAL IDOL'S SIBLING, MAKE THE FREAKING RESEARCH!

I cannot even count how many OCs are ruined because the author just randomly wants to add them an idol sibling. I just suggest not to add idol siblings at all. They ruin your character very easily. And if you do add them do as much as research as you can! The same applies to idol friends too!

I made a character that has idol siblings actually two of them just to prove myself that is possible to create a realistic character having idol siblings. It is possible but requires a lot of work. I made plenty of research to make her realistic. Everything that I added has a reason and spent probably hours researching things to make her as realistic as possible. If you want chech her your here: Jo Somin

2.

This second one is just gonna be short. When deciding audition links for your OC, think them carefully. Female OC can't have male singing or rapping links, there's quite big differences in female and male voices after all. Also dancing links should be from the same gender too. That's not mandatory like with singing and rapping links but adds lots of realism to the OC. I would definedly recommend using the same person in all singing links and all rapping links. Every person has a different voice so it makes just much more sense.

Don't make your OC too talented in every area. Rapper probably isn't that good at singing and a vocalist probably can't rap at all. That's just realistic! If your character is main vocalist you don't need rapping links. Also if your character has voice like IU, dances like BoA and raps like Jia or CL. Well... There you've got an Mary Sue!