What are everybody’s tips on effectively saving many  streetlight fixtures because I am starting a project doing just that for northern Virginia

The method to saving them depends on where they come from. If you are trying to get them from a large utility, the chances of being able to do so directly from them are slim to none. This is where you're best off finding which scrap yard they go to and buying them from there. I've saved quite a few lights that way. Most scrap yards are happy and willing to sell whatever comes in at a slightly higher price than what they get, as it makes them a profit.

If you are dealing with a smaller utility / co-op, asking them directly doesn't hurt. Oftentimes they're totally fine with it. If not, refer back to scrap yard method.

 When it comes to lights that belong to parking lots apartment complexes, hoa's, Etc, your best bet is to contact to the owner or somebody in charge and leave your info. Also respectfully explain why you want them. This is my most successful method, I have been ghosted a couple times but I've never been told no. Nowadays with a lot of environmental regulations, it costs money to get rid of these fixtures because of mercury and PCBs. Usually the person in charge of the property puts me in contact with the contractor and they are very happy to find somebody willing to take them off their hands at no charge. If you can't get in contact with anyone, wait till they are taken down and ask them directly, or if they're sitting in a dumpster ask somebody in charge there if you can go grab it out. But the most important thing is that you ask somehow because the worst they can say is no.

I appreciate your recommendations I have tried privately owned lights and they will try to save 4 fixtures for me an OVX and 3 ov25s, I did have an idea of going to the utility station and talking to them and see if any line workers would be willing to help and maybe even make flyer

I have sometimes seen old street light fixtures show up on Facebook Marketplace.

I’ve seen them aswell but nothing cool is for sale in northern virginia

As mentioned any kind of resale platform such as Facebook Marketplace is a good place to look for streetlights. Other places I've found and bought streetlights from before include: eBay, Habitat Restore, antique stores, and stores that deal with surplus electronics/electrical items.

As a matter of a fact I actually already am saving streetlights, I found a lineman friend that helps me save these fixtures, I’ve got 9 total