Use "preferably ___" to talk about something that you want but isn't absolutely necessary.

I'm looking for a job in the fashion industry, preferably with a salary of $65,000 or higher.

Can we get together to discuss that, preferably some time early next week?

Take some medicine for the pain, preferably aspirin, and if it continues call to schedule a follow-up appointment.

"Preferably" usually comes on the end of your sentence. It can't be used as the subject of the sentence.