Declaring VA Domicile

If your desire is to keep Virginia as your domicile, you need do nothing. You will need a mail forwarding service, otherwise I dont believe you need to do anything. Keep and later renew your drivers licenses as you normally would, you will have to continue paying personal property taxes and purchase county or city license fees according to where you establish the mailing address. As long as you are paying state taxes, Virginia will not disown you. Licenses, personal and professional, voter registration, anything that demonstrates your intention to return to Virginia frequently are the things you have to actively change to become something other than a tax paying Virginian.
You already are a Virginian, you will continue to be until you change it.