Just to clarify- be very gentle with any manual assistance, & only after misting or soaking to soften the old skin/eye caps, so they're easy to remove. If eye caps remain in multiple layers, get the help of an experienced herp vet so as not to permanently injure/damage the snake's eyes. If old skin remains on the tail tip, it can quickly cause the death of the tissue there (it doesn't take much to cut off their limited blood circulation), & it may require amputation- prevention is essential.
Nostrils: Many keepers don't realize that the outer lining of a snake's nostrils gets shed along with the rest of their old skin. Sometimes you'll see a tiny bit of loose skin that you can catch with tweezers (carefully!), or sometimes the snake will exhibit noisy breathing as a result of that bit of skin remaining in their nostrils- fyi.