How to use the secured cards to my best advantage?

[tjdutch]

Well I opened up 3 secured credit cards. $200 secured from Orchard bank, $200 secured with Household bank, and $300 secured from Applied Bank. How should I utilize these cards to effectively boost my credit score? Do I only use 30% of these cards a month total? for example, just use 30% of the $200 dollar cards which would be $60 a month, and use 30% of the $300 card which would be $90. I want to build my rebuild my credit and plan on paying on time every time. Could I charge less than lets say 30% and still build my credit? Or would it be best to use the card a lot and pay it off? any suggestions would be most helpful. Thanks