To reiterate what Jaysen said, being genuinely interested in people goes a long way at networking events with regards to the impression it leaves on them. If you're only out for yourself and have a clear agenda, you'll be spotted from a mile away
Just go in with an open, friendly and honest demeanor and people will respond to you. The first few events I ever went to, I was really nervous about networking. I wasn't sure, especially with the more senior people, how I could possibly have anything of interest to say to them. But after being to quite a few, I've come to realise that people mostly just want to talk. You could talk about their (and your) career interests or trends in the marketplace or simply make conversation about day-to-day things like where they come from or live now etc. Obviously at more tailored events (e.g. a LawTech seminar) you'd have pretty set things to talk about already but really there is no magic recipe or tick-sheet to follow, it's just about being relaxed and having a conversation (and, depending on the event, a free beer or two)