Watching good players play her can give you a good idea:
You'll see that Ain uses 2P, 2H+K, 6P a lot to start his offense.
Good moves to start your FLA pressure even on block: 4P+K, 4K, 3PK, 8K, H+KK, P+K
When you enter FLA focus on:
P to keep your offensive going or to stun them further. If they're trying to mash their way out this will also hit them a lot. You can do anything after this, really. Also good for tick throws.
P 2KK or 2KKK to get more stun or a quick combo
3k after they start holding high for a quick stun+combo
2K or 1KK also good options if they're expecting your P stuff
2/8P+K to evade linear stuff and maybe even get a free back combo
Step -> OHs
Sarah can get them in the stun threshold without doing much work, really. But don't always go for a CB combo, I think she has a nice stun -> launch game, which is less risk and does good damage.
For example, 6P on CH, 2P+KK combo or FLA 3K 2P+KK -> combo