If your a new user to creatine, its a good idea to saturate your muscles with it before hand by creatine loading. For between 4-7 days, take 25 grams of creatine divided into 5 doses. Make sure to drink plenty of water when you take it. A gallon is good, 2 gallons is better. Then after the loading period, if your not a serious competitor, just do as chris2489 says: use it till you run out.