>>2937565OPie here
An interest in my locality's derelict buildings led me to develop an interest in local history, but being familiar with local history and the industries of your area will help. It is vital to explore your town from the street to determine where the abandoned spots are.
Once a building has been found through research or by just finding it, find as much information as you can on it: If a site is earmarked for development then there's likely to be security. There are very little security measures on the ones I've been in, and it's common for people to explore and vandalize, as prosecutions are rare.
Unless there are some very interesting historical artifacts which would be in danger if left behind, Take nothing but pictures, leave nothing but footprints is a good policy to follow.
Respect the buildings, their history, and their future