Is it true that in DND gods are more of a "if you're needing help in 'x', you'll pray to 'y'"? So if you're in a dark alley trying to get home safe, you'd say a quick prayer to Shar to help you home?
N7Greenfire is correct about Selune in this instance... But that's not because Shar is evil, nor that she wouldn't answer the prayer....
Many evil Gods are being prayed to by non-evil, non-followers: Talos [Storm] and Umberlee [Seas] for instance, would be asked to stay their hands as the praying ones embark on a voyage. But Shar is the God of Night, Loss, Secrets... She is weird.
I have struggled with trying to come up with a scenario where a non-follower would pray to Shar. I could not think of one. Shar is weird. She's also one of the most important Deities in the Forgotten Realms, with probably the most written about her.. But Shar remains stupidly weird.
Yes, night - but not for navigating the Stars, that would be Selune again. Yes, loss, but no 'Prevent loss for a tithe' or something. That's not how she operates *at all* Maybe secrets? "NIghtsinger, help me keep this secret?" Yeah, possibly. It'd have to be something awful, though. Like; 'I secretly hated my mom and stabbed her in the eyeball but now I miss my mom' and there is no one else to pray to.