Go to every event. For me I was a bit apprehensive spending that much money, but it really is a very different state of affairs to the rest of the year. Like you'll do stuff throughout the year, and you'll likely enjoy them more, but Freshers is invented for spending literally hundreds on alcohol, tickets and pizza. Don't regret it.
Also you don't have to do club nights every night. I went to a jazz night with a flatmate, and I thought my flatmates would think us weird but they didn't really bat an eyelid, and it was my favourite night!
Easy sex if you're up for that. To be honest your flatmates will think you a hero, so you might as well.
Oh, and make sure you actually know what you're supposed to be doing and when. I had tonnes of registering for absolute rubbish. One was a medical thing and I was in a seven hour queue for it (machines were down), so bring food maybe? I dunno, really just go with the flow, you can't plan too much because it's so fast-moving.
Finally if you're short on conversation, mock people's accents. God knows why, but it's all my flatmates did during intro week (I don't even have an accent). And pointing out how awkward the whole situation is kinda works, where people come from, their course, etc. I know it's all chiché and cringey to do it again and again with dozens of people you won't remember in an hour, but it's worth it.