I tried my skin on for the very first time today so I had been thinking about this yesterday when my permawet was drying.
Being a performer and luckily having done a small amount of suit work before I knew that the underwear was important, I had access to a personal cotton-lycra unitard (neck to wrist to ankle bodysuit) and I had no real trouble even with the small amount of latex that had leaked through onto the interior when putting it on.
Only problems were my exposed skin on my hands when trying to put on the sleeves, so I'd recommend trying to cover as much skin as you can.
I'm hoping keeping yourself covered will also help protect the interior from degredation due to the sweat and oil from your skin by minimalising your direct contact with the suit itself =)
I tried a unitard on my first suit and honestly it was kind of a pain. On my next outing I wore two piece under armor... The kind designed for warm weather.. It worked great... Then for my pred outing at wondercon, I just wore a t-shirt and gym shorts.. That actually was the easiest. Any cotton or Lycra, you will sweat through... Just wipe your suit down after you wear it. The under armor is probably the best way to go
i wear lycra leggings, cotton socks, cotton gloves and a cotton long sleeved top. i wouldn't advise having skin touch latex, and not coz the latex might degrade quicker, you'll never get the bloody thing off, and no matter how much baby powder you put on eventually even that will fail.