First, you must walk as if the weight of the world is on your shoulders. Of course, it isn't. Your heart and shoulders are light and carefree, so carefree, in fact, that you won't mind the inevitable downpour you're bringing on yourself and everyone else who shares your weather. However, you should assume the posture of a street light in anticapation of the increasing barometric pressure you thunderheaded thoughts are generating.
Dressing for the approaching storm: Your clothing is a function independent of the rain cloud you're attempting to gather. For the most part, adorn yourself in raiment indicative of the excitement that coalesces around a theme party particle. Really, whatever you deem appropiate will be so. If it feels like a wet t-shirt storm, then wear a white tee. If it feels more like a wet prom dress run through, make it so. It will be most certainly be soggy though, so over-sized black boots are a necessity and it's best to leave them untied. Let's let your friends in on it too.
The last and most important parts of the bringing the rain cloud are a full belly and an empty bladder. It's important to feel grounded. One of the realest and most visceral ways to do that is a hearty meal. However, since you'll be focusing on fluid transfer, it's best to go to the bathroom before leaving the house, at least to pee. You don't want to wet your pants accidently while you're willing the sky to transfer fluid to the earth.