Don't use oils of any kind....bad for you grip.
You just have to work your fingers under it, and work it up and around the leg...get the leg openings where you want them, then work on pulling it up from there. It usually takes 2, maybe 3, of us to get me in my suit...and it's not a fast process. Once you have it up around your hips a little, you can have someone pull up from the front, sides and back, then lunge, sit back in it, etc...to work it up more...then have them pull again. Eventually you can loop one strap over a barbell while the other person hangs on it from one side of the barbell and you hang in the suit from the other side. That usually gets the sides smoothed out once you're done.
....it's exhausting.