I have awful problems with this and I hate putting them in my nice clean, orderly linen cupboard, however I have a problem folding any sheet on my own.
I even went on line and watched several videos on how to fold a fitted sheet, however still could not get the hang of it. It looks so easy when you see them do it, but try it myself -just did not turn out and I gave up in disgust last week!
I fold them as demonstrated by the image in jonaj's response. They never look 'that' neat though! They are a pain in the neck. When it comes to other sheets. I try take them off the washing line in way that makes folding easier.
Same as Finy, I have watched the tutorials to no avail. I do as jonaj does - I roll them. Even when himself helps me to fold them they look dreadful, so rolling actually is easier and stores efficiently too.
I actually fold them while they are still on the line!! I have always done all large items like sheets, both flat and fitted,towels etc,this way!! I just lower the line right down.and then do them!! Easy-peasy,especially for someone like myself with extreme arthritic problems!!!!