Theres really no set way to go about it. Several good methods have been suggested. One important thing I think no one has mentioned don't go crazy with distortion. You want to add little distortion but in multiple stages. I personally don't really load my bounced samples into a sampler because I like working with audio. There is advantages to both methods, though. Also, if you layer real sounds with high frequencies such as paper crumbling, water running, etc it will give a great texture and movement in the hi end.