yeah, realize that it takes time, and sometimes what you pick out has to do with your current state of mind/emotion.
Like i skip samples all the time because im not feelin them, but if i revisit, i can turn that same sample into a banger, when i couldnt first time around. Alot of times it wasnt like i didnt realize that the sample was good, i just didnt feel like doing it, so i wasnt gonna force it............
sample anything that gives you immediate inspiration or evoke emotion.
dont force anything
dont limit your self
dont set hard and fast rules to sampling like: "i only sample soul records" or "i dont make such and such style of beats!"
listen to your emotion and feeling
experiment
dont be afraid to put things on the back burner and revist (make sure you remember or mark where the sample is though!)
I think that your ear is developed by listening to things you like. I mean, think about it, if you enjoy sampling it, you are gonna do a good job, or atleast have inspiration to do a good job. you gotta channel that inspiration and emotion into the beat-thats what a good ear does!