Does anybody have experience with being granted access to private lands? People who work /out/ jobs might be able to give me some wisdom here...

State/Federal land, individual's private property, places managed by private groups, .... (and access to closed areas, like Wildlife Refuges/State Parks after hours)

Is there a "professional" way to go about contacting the people in charge of these properties to get access permission?

I'm a wildlife photographer working on a field guide for my state's reptiles and amphibians. I'm not looking to camp or anything - just looking to get access to prime habitats to photograph/document species, which are usually on private property or restricted areas of parks/refuges.

Can I get something like a research permit (as a private individual) from my state, which would give me some lee-way when asking for land access?

As a dude in my mid-20's, I often feel like the old folks that manage most of the land don't trust me.

So, is being granted land access all about people skills and connections, or is there some kind of paperwork I could get to help me out (particularly on state land)?

Sorry if it's a long and boring post.