Donating Blood?

Zerenity • 28. Arizonan. Army Wife 💍
Okay, so it's been about 4 years since I've donated. I have O Positive. Does anyone recommend anything the night before what to do and so on? I don't remember. I absolutely HATEEEE needles, but the RedCross offered a gift certificate for me to redeem in return for my donation. 
Anything helps.(: 💕