-Spindash to spring isn't quite exactly your best option. Spindash>up aerial>spring up aerial can work if you read their airdodge after the first up air.
-If you're a player who likes to focus on spindash and run away a lot, you'll want to resort to spindash camping fairly often. If you get a lead, position yourself across the stage from your opponent and charge down b. Wait for them to either almost land on the ground or spotdodge, then release and try to hit them to before they land/ before they can shield after the spotdodge. Spindash is a good tool to use against landings onto the stage. Follow up your spindashes with up aerials>more up air juggles or with a forward aerial. You can attempt a back aerial, but this is better saved for higher percents so you don't stale back air as a kill move.
-An important aspect of a spindash-based-sonic style is proper use of shield cancels. Spindash shield cancel (SDSC), reverse spindash shield cancel (RSDSC), and aerial spindash shield cancel (ASCSC) are your most important tools. These are all to fake out your opponent and make them think you're approaching- I believe I remember Malcolm once saying something about how "Sonic has a million ways to make you think he's approaching, but no ways to actually approach".
-Basically, you have to force your opponent to make a mistakes via fakeouts, and punish it with either a spindash, dashgrab, or some sort of shorthopped aerial if you're close enough.
