I've got a cheap, black, hardshell case I want to paint my name onto. I figure I'd make the letters white. Would it just be electric tape everything I dont wanna spray, spray it with white a couple of times, remove the tape?
take painter tape (the blue masking tapes) a thick one, cover up a big portion of where you want the writing. draw what you want to have on the masking tape. then cur the part that you want to spray. cover up any other exposed parts with paper and masking tape on the edges. spray away, let it dry a bit, and you're good.

i forgot how i did it, but i believe i sprayed, then ripped off the masking right away. i think.

i think you should use white primer instead of just white spray paint, because primers stick well and they're strong. dont spray too thick though because it'll be hard to peel off the stencil.
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What kind of case? Chipboard or plastic? Either one is likely either a plastic shell or vinyl covering. In that case use something like Krylon Fusion. It bonds into plastics so it won't rub off over time.

Here is one I stenciled and hand painted.

Since the case has some texture it's hard to avoid at least a little bleeding.