Increasing Credit Limit - Good or Bad?

Hello,

 

I recently saw my credit score decrease ever so slightly due to my increased "usage" - calculated as a percentage of my credit limit. I was interesting in increasing this limit (assuming that I would qualify), but was wondering what the impact of this would be on my credit score (whether it be good or bad). Also, how much of an increase should I request (should I just do the max I'm eligible for or is there another formula that can be used)? 

 

Thanks!