Yeah, don't kiss ass. They're used to that and it invites disrespect. If any of your professors like to hang out with their students socially that's probably the easiest way to get on their good side. Hanging out with professors can feel like networking depending on their personal style, but if they're clearly out just to cut loose and bullshit talk about what they're interested in outside of work in a way that lets them do most of the speaking. Most professors have massive egos and you can use that to charm them. Make one of these people your graduate advisor if possible, then it's their job to look out for you. There are exceptions, but the more "important" a person is in academia the less time they tend to have for students, so it's best to talk with students who currently have them as advisors first. The professor who seems like the best match for your academic interests may nevertheless do little to help you. If applicable, join research groups the professors you are interested in are involved with. Nothing impresses a professor more than a student that takes work off their shoulders. Enter as many scholarship and paper competitions as you can. Professors love to be able to share in the credit when their students place top in the nation or near it for an article/conference poster/whatever. Short of that, just doing better than the other students in your program on select projects the professors are especially interested in will suffice to draw their attention.