I agree that a sample set would seriously be the way to go. By skincare, do you mean just for face?
I'm fair and sensitive-skinned, but skincare really (and i mean REALLY) is on an individual basis. I find that products for aging skin tend to work well on my sensitive skin (I'm only 24 so it's not an aging thing. lol) Some of my fav. sensitive skinned products are:
-KISS Cleanser (which is really best with the foaming bottle. This can be a little drying, but shouldn't be an issue if she's moisturizing)
-Any of the hydrating serums (which are gentle and add moisture to dry flakey skin.If you're building a sample set, I'd let her try all 3)
-Any toner with fruit in the picture (unless she has acne issues or skincare issues, i'd stay away from the acid toners on sensitive skin, because I've found they have a learning curve and unfortunate results with acid toners can
really hurt)
-Any of the masks (they're all pretty gentle on skin, indulgent, and fun)
-The moisturizers are kind of a free for all depending on whether or not she needs extra moisture or needs to be acne conscious. I actually use the lavender hand lotion (while the moisturizers are lovely and i've fallen in love with several of them, i've found when i use them regularly that my skin isn't altogether in love with emulsifier in the gel base)
-I would totally add a black label lip balm to the mix. They're wonderfully moisturizing and come in clear flavors like devils food cake(chocolate) and peppermint.
Sample skincare comes in little dropper bottles, and a lot of SN comes in a sheer drawstring giftbag and/or wrapped up in pretty tissuepaper. If I were building a sample kit for myself, I'd put in a sample bag each of the masks (4), a sample toner (pore refining), A sample of the oatmeal hydrating serum, a bottle of lavender moisturizer, and a devils foodcake blacklabel lippie. Those 9 items come to $16.19 before shipping. You could still add in extra samples of serums or moisturizers for variety. *Bonus is that it will come prettily packaged with a gift-with-purchase(usually vegan eyeshadow) and a makeup sample.
Of course there's lot more to consider than just that her skin is sensitive- does she have problems with acne, rosacea, or dryness? Is she scent-sensitive/does she prefer unscented things? Were you wanting to get her head to toe skincare (there's body butters, cuticle creams, haircare, etc.) and when you say she's fair, were you thinking makeup?