I find that Star Tours always seems to have a decent wait, even when you use a FP. So, if I was there at rope drop and wanted to do both quickly, I'd probably just do Star Tours standby and then do Space standby (should still be short if ST was walk-on) and not bother with FPs immediately (grab them if I wanted to ride again, though). If I was doing other stuff, I would grab a SM FP, do my other stuff, grab a ST FP on my way to ride SM, ride Buzz and then use my ST FP.
As a general rule, if we arrive later, then I would go for a SM FP first, as they may not be available later in the day.