For running routes, if I'm somewhere new, I'll often go to a bookshop and buy a local walking/hiking book and just follow those. I just got back from a stay where I ran a lot of the north wales costal path, for example. Cicerone Press make good and handily small guides. If I'm learning a new run, I'll often jog/walk it for a few miles from my car, learning the turns off and tricky bits, and then turn round and run it back to my car.
For slippyness, November tends to be particularly tricky with all the wet leaves on the ground. I'd take it pretty slow and always have free hands to be able to help you fall, if you carry water/phone/map etc take them in a running vest do not hold them.
I'd also really recommend doing a few ankle flexibility exercises every day. I do mine while i'm brushing my teeth, it doesn't take very long but does mean when you hit an uneven step you are more likely to be able to counteract it. easy ankle strengthening exercises
I'm not sure if by trail you mean eg round the local football fields or a bit more off the beaten path, but unless you are confident you are in easy shouting distance of help at all time, I would take my phone, a whistle and a blanket every single time, just in case. It is amazing how quickly you can get very cold if you sprain your ankle and end up lying on the wet ground, for example. A lot of hydration vests have a built in whistle if not you can get one for a few quid on amazon like this
Likewise an emergency blanket is smaller and weighs less than a packet of pocket tissues but is incredibly useful just in case the worse happens. I have never had to use one, but did once use one to help a fallen hiker and I was so thankful to have one on me that day