"Don’t petrol bomb anything, and you’ll probably be grand."
If you see more than 5 PSNI land rovers, or a water canon, going in one direction, you go in the other if possible. If you hear dogs barking like crazy, strange sirens, or loudspeaker calls for a crowd to disperse, run like fuck in the opposite direction.
Don't buy alcohol from the boot of a taxi, at a house party, no matter how much everyone says it'll be fine. Don't drink home brewed poitin. Google the closing times of the last pub/club, you plan to visit, on a night out, and pre book a taxi, as they can be hard to get at kicking out times, and their are some dodgy illegal ones, that pick up around the city centre.
Everything else I could say, would just be standard visiting a city common sense stuff. Those last few things I last probably are too.
Actually, I've just thought, the buses back to Portrush etc, from the giants causeway, don't run after about 6.30pm, so worth making sure you know return times, and don't get stranded in the middle of nowhere.