Go on the york walls, they are the best way to see the city and if it is nice weather it is an amazing view!! Make an effort to go out and socialise for the first few weeks - even if you are not typically a social person, it will really benefit you to make friends early, particularly if you befriend the people you live with

Eat together with your flatmates - some really fun experiences happen while cooking/eating together at uni. Look out for student drink deals when out in clubs - and take advantage of student discount in shops! On the academic side, keep up with your work and use the quiet times in the day for reading, drafting essays etc. It will pay off in the long run. Also, get into the habit of going to lectures and seminars in the first year - tutors do tend to notice the students who do not show up and you might need the knowledge when it comes to final year