Eye contact depends on a few things for me.
My tip is to look when you can, even just glances and PICK ONE EYE. Sounds strange, but it really worked for me. I used to look all over the face and people notice that, so now I only look in the left eye, always, then look away, then look back. It honestly seems more natural because you are seeming confident rather than nervously indecisive about where you look.
The other factors for me are;
First is how comfortable I feel with the person, huge difference in my ability depends on whether I feel comfortable or uncomfortable.
Second is who is talking, I can look in the eyes (well left eye) if I'm listening, especially if they look somewhere else. It can get too much if they are also making eye contact & I feel myself staring, but I don't think its very noticable to them.
If I'm talking I can't make eye contact and make sense at the same time, so I look up into the left eye at the END of each sentence, after the words are out. However if I'm talking about a special interest I forget eye contact, almost forget the other person is there once I get going, but that would have to be someone I'm really comfortable with to start with so they don't mind, I think.