Some systems have complicated systems of merits and flaws to create more rounded characters, ones who have disadvantages balanced with other advantages. If you find these too much to administer, or your chosen ruleset doesn't have one, this is worth a look. Whilst being designed for the D20 system, it could be introduced into a different game system with little modification, the concept is sound.
The basic idea is simple. No character is absolutely perfect, and so you can make a random selection of up to two flaws from the tables herein. (Any more than that would tend to be a bit silly, but the odd defect can help improve role-playing.) To balance the disadvantages - generally presented as negative modifiers to either skills or attribute bonuses - an extra feat may be taken for each flaw that you have.
Some are a bit odd. For example, the flaw of being intensely curious is handled mechanically by giving a -2 modifier to listen and spot checks, being always the last in combat and having a -1 to ranged attacks. Now, I can understand going last in combat, but surely a negative modifier to your concentration check would make more sense than listen and spot ones - reflecting the ease with which you are distracted, after all you might be very good at actually noticing things hence being distracted by them! Most, however, have considerable potential for bringing your character to life, provided that you role-play being a fussy eater or a loud-mouth as well as taking the mechanical hits for your disadvantage.
Interesting ideas which you may wish to develop further to fully incorporate them into your game.