You need to make a nice skin, be attractive to pilots, have dedicated staff, preferably a fleet that does not include the Concorde, A225 Antonov, Airbus A380, B744 (you get the point)
In the end, post more info about your VA, tell what you offer etc.
If it is a good VA pilots will come on their own. Its your job to make them stay.
Good luck!
It is harder than you think,
I know, because I myself am having a hard time doing that.