If the thing ash is protecting is unadvanced, it could be adonis. Consider making the trace so they'd end up with $2 if they pay through it. Or consider (especially if you have an interns in hand) making it so they'd end up with $5 if they pay through it and could kill adonis or ash but not both.
If the thing has one or two advancements, make it so they'd end up with $3 and couldn't steal NAPD. Obviously if you're protecting a 5/3 and you're enough richer than the runner that you can afford the full trace, you don't take that risk, but frequently you'll be more evenly matched and you need to bluff. Better still, perhaps you're on 4 AP, so NAPD wouldn't be game over, but if they paid through it and couldn't steal NAPD, the tempo hit would also give you a scoring window for atlas/ABT right afterwards.
Caduceus is another great one to boost by 1 or 2 or so. Against criminals you can do it to make their sec testing unprofitable. Or if there's unrezzed ice behind the caduceus, you can set the trace to make them $1 short of passing whatever's behind (or use it to bluff that a bigger ice is behind the cad than actually is).