OK you can Invent your own Cards, it's amazing. But Don't go over the top...
Template:
Card Name: (Self Explanatory)
Card Type: (Monster, Spell, Trap, Ritual, Fusion, Synchro, Effect Monster)
Attribute: (Light, Dark, Water, Fire, Wind, Earth, Spell/Trap)
Level: (Monster Only...What level is the Monster, number of stars.)
Type: (What type is it? e.g Fiend, Warrior, Spellcaster, Beast, Winged Beast, Thunder)
ATK: (MONSTER ONLY! what is teh ATK of the monster?)
DEF: (Monster Only, what is the Monsters Defence?)
Description/Effect: (What is the Cards effect or Description)