This is where the powerups are going to be come into play. Without them, reaching a gold star cutoff is impossible.
The powerups you'll want to use depend on the song itself. Anything that uses Overdrive energy will mean you'll need to constantly switch tracks to grab any white notes regardless of the multiplier to get the most potential out of extra scoring.
For purple notes, this entirely depends on your playing style, however you'll want to use Blast Notes, which are good for clearing out nearby notes without too much switching, and Chase Notes if you're more likely to switch on the fly earning the 10,000 bonus upon successful capture.
This will mostly be about experimentation more than how well you can play. As it is, watching a high score run when it's available should give indication onto what you should be using. Examine the song first, and then decide where you should be to exceed to gold stars. Purple Notes do not change between replays, but they also are in different spots depending on what you use.
For a more in-depth look to each song and its respective cutoff score, check this thread.
Note: This cannot be earned if not connected to Rock Band Central, as scores will not be updated/saved.