Well obviously as Sheik having someone in a grab is never a bad thing. But to answer your question, imo I don't think ftilt would be a very good idea unless well spaced. I don't believe it has good frame data on shield. You're on the right track about fade away fair. You more so wanna use autocancelled fairs, because you can do literally anything out of it. Grab, jab, jab>grab, tilt, wavedash, dash back. It's easily one of Sheik's best tools. Something I've seen, but wouldn't recommend, is pressure with uptilt, since it's quick and has multiple hits. It's def not a fantastic option, but it's been done. Another thing is, as far as I know, Sheik isn't much of a shield pressure character, so that's something to keep in mind.
I'm not an expert on Sheik by any means, I'm sure someone can chime in with a better idea of what you can do.