How do I talk up random HBs at uni? What should be the mindset, how much risk should I take, how quickly do I escalate, how much comfort versus attraction? Stuff like that. Experienced guys please help. Thanks.

_________________
"no pain, no gain"

Do what fits the scenario.

I have just sat next to them in class, gave a pie to one of them, and just see them in general throughout the day outside

I will assume you are talking day game so take your time to escalate and focus more on comfort and numbers to be able to hang out with them at a later time

The funny thing is that I took too much risk and hit on too much girls. Since it is a close environment, it already happened that I hit on the same girl 2 times.
But don't care, go for it. The same principles as elsewhere apply

"Hey guys, you going x party tonight right"
"Hey guys, know where x building is, btw..."

To be fair, situational openers are the way to go, as there is always a lot on in university, so its more flowing and real.

As for the the inner info, Uni is fun! So, i would go with more attraction, more kino, quicker interactions, and use comfort in shorter bursts. Remember the Lyons princliple of attraction, use social proof as much as possible, if you dont have girls with you, keep your interaction brief (unless there going very well) and play the room, more girls see you with more girls, this will set you up for the night, and the next night and so on.

Assuming this is for one night stand type of deals.