Ok, I've been seeing really crappy OC's (original characters) floating around the place lately. I thought that I could help you guys out here.
-What is a original character? It's a fan-made character someone usually makes for a book, show, game, etc that is used as a means to "interact" with the main characters of a book, show, game, etc. Unfortunately, some people get this wrong and their character/self-insert may become a Mary/Gary Sue.
-What is a Mary/Gary Sue? Well....they have the following traits:
-The plot of the book, show, game, etc goes THEIR way (If this only briefly mentions a canon character and is more oc-centric, it's usually ok)
-They have NO weaknesses
-Any and all characters are attracted to them
-They have a TRAGIC past
-They are a long lost relative or are the long lost lover/girlfriend/boyfriend to a character or more
-They die a TRAGIC death
-Every good guy and bad guy likes or loves them
-Immortal, can bring people back from the dead
-Is a vampire/werewolf/fairy/princess/dragon/prince/god/goddess/zombie/unicorn, etc OR all the above!
-Often have a very over-used name
-The canon characters are ooc (out of character)
-This list is too painful to write more, but I'm sure you get the idea.
-Creating your character, Starting traits-
What is their name and/or nickname? If you name your character something like Sakura...go back to the name board! Also, do NOT match names with personalities!
Their age? Try not to make them YOUR age and birth date!
Height and Weight? If you don't describe these, often people will assume this is a self insert of YOU and may assume that you are VERY fat. So make this believable.
Species? Don't hybridize your favorite characters. Otherwise, they'll just end up a BLOB with eyes over here, a mouth over there, and twitching, useless limbs.
Hair color? PLEASE refrain from using a fake hair color (unnatural) or from making it the same hair color as your character's crush.
Eye color? Again, do NOT make it unnatural (like red)! ONLY make it unnatural if it's in a fantasy world. If it's oh...a world of cats, colors like yellow, gray, and (rarely) whitish are ok.
Clothing style? People won't take you seriously if you have them in ALL black or if they barely wear anything. If this is a animal (not a humanoid animal, but a ANIMAL animal), state if they're wearing something like a collar (avoid spiked/studded/chained collars).
Place they're living at? People won't take you seriously if you have your character in a place you want to live in. Like Japan.
Back story? Don't make it tragic unless it makes sense and doesn't go overboard. Also, if they have had any interaction with a canon character...Don't make them past lovers or some other junk like that!
Personality? Avoid matching this with names. Seriously.
Powers? Under NO circumstances should you make them immortal, have unmatched powers, ultimate healing skills, etc.. Make it a skill that they've been working with. Like uh....the ability to balance plates on a stick.
Weaknesses? This is very important!
Historic significants? If your character is something like a country representative or a solider, please do your research!
Remember, you should not make them look like a canon character! That's like dying Sonic green and calling it your OC!
OC examples- This will show you good and bad examples of OCs.
Name: Anna Herring
Nickname: Ms. Fish
Height/Weight: 5'3"/230 lbs
Hair color/eye color: Auburn/Hazel
Clothing style: Casual and modest
Current residence: Houston, Texas
Back story: Grew up in a small town and went to collage. Her family lives in Austin. She has three siblings: two brothers, and a sister (Names are: Fred, James, and Sarah). Anna works at a veterinary clinic.
Personality: Very curious and bold
Weaknesses: She has a really bad cavity and has bad year-round allergies to the pollen.
Historical significants: n/a
Name: Katsumi (Victorious beauty) Yuzuki (Gentle moon)
Nickname: Sexy goddess
Age: (1,5)32,783,278,937,284 (if it's a "immortal" age and has anything from 1,1 to 1,6...you're basically hiding YOUR age)
Height/Weight: 6'2"/ 90 lbs
Species: Human with hints of elf, vampire, and dragon.
Hair color/eye color: Pink/Yellow
Clothing style: Sexy and cute clothes
Current residence: Japan, baby! Yeah!
Back story: All her parents DIED! She's BFF's with Naruto, Ichigo, and Sonic. Her boyfriend is Megatron. She's married to Gary Oak! It's ok though because everyone likes her and even fights for her LOVE!
Personality: Cute, innocent, flirty
Powers: She's immortal. She's got like the ability to speak to animals! She can run really fast and fly. Oh yeah! She can breath fire and if someone dies, she can bring them back!
Weaknesses: What weaknesses?
Historical significants: She's the reason (insert war here) started but she stopped it ALL by herself!
There you go. I hope this guide has helped!