It's very hard and it took me until junior year of high school to be decent at making eye contact. I'm still not great at it and I never will be, but I figured some of it out by trail and error. You can time yourself and make eye contact for a little bit (I started off with 7 seconds minimum) and that stopped my friends from making me uncomfortable. I also use a lot of gestures when I speak so I can disconnect eye contact for a bit, reconnect, and disconnect so I'm not starring the whole time, but seeming social.

It seems to be socially acceptable to move your eyes away from direct eye contact to think of something and to remember things every so often. This is what I do along with gestures and it seems to be working out decently. Passively (not being a creeper) study other peoples behavior and try to learn what they do. I hope this helps!