I think it might help to bring rope or paracord in case you find a situation where you feel you might not get back out. I wish I had brought some on my first explore at an old pulp mill since the only way down to the bottom of the structure was a little dangerous.

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Here is the way down I had to take, to the left there was a +20ft drop to the ground floor and where I need to hop down to was about 6ft below me and right under the ledge was a gap in the wall that lead to a +10 ft drop. If I made one wrong movement, I would have had a very very bad day. I (stupidly) decided that the best way to make sure I could get back out was to climb down then back up without my backpack. Why I thought that would be a good way to test it, I'll never know. On my way back up to get my bag I almost trapped myself since the only foot holds to get up were covered in ice and just so happened to be the little wall you can see to the left dividing the 20ft drop and 6ft drop. Yikes! Obviously I got myself out of that but ever since, I bring some rope with me in case I feel like exploring somewhere where I might not be able to get out of.
All in all, I would say to always bring equipment to get you out of such a situation and use your best discretion and a good knowledge of your abilities to determine if you may or may not be able to get out.