Okay, I'm no expert, but I have spent years (and years!) trying to find the right foundations and my best advice is that you really have to get hold of samples.
With dry skin (I'm combination), I think I'd point you in the direction of the serum foundations that have popped up over the last year or two. I'd also not overly worry about skintone unless you go with a brand that puts skintone in the spotlight (e.g. Bobbi Brown believes that yellow should be everyone's base).
QVC's shade pics are awful. I'm pretty sure they used the same pictures for the Doll 10 show yesterday as some of the Tarte shows and I'm NOTHING like that shade the show as the one I need to buy. But at least for a few quid postage, you can return if something looks awful on you.
I bought the recent Tarte TSV which has the serum-type foundation (they usually have a dropper type bottle). As a guess I got the Fair Light Neutral and it is pretty neutral. I no longer go by the pictures, but always study the shades if they're swatched on the back of the presenter's hand. My skintone confuses all but the most seasoned assistant as I'm neutral to warm toned, but have a lot of redness. They take one look at my face, see the redness and stick me in a cool tone in an effort to match it, but then I'm a horrible contrast with my neck.
As I'm getting older I'm finding myself drawn to the brands with fewer shade choices, too. I get samples - even if I have to buy them from eBay - and try them on in broad daylight. I'll then check in different mirrors and lighting through the day to see if it changes colour on me (this is probably the worst thing a foundation can do as I really look a mess with a Tango orange face and a neutral neck!).
Most days I use one of Garnier's BB creams. Although there is a slight difference in shade across the range (I have the normal spf15, the Blur with a primer version and the Sensitive spf25 version), I use Light and my face still looks "me, but better" in all three. It's these creams that have taught me to be able to pick a shade on a hand swatch sample. I have no idea why I haven't been able to do it with any other foundation. They're also reasonable enough that I can use a blob on my hand to swatch against foundations in the shops.
Sitting down and slapping it on in store has never worked for me. The assistants almost always put me in several shades too dark for some reason. If they won't give me a sample, I'll check their policy - some brands WILL refund you if you're unhappy. If an assistant tells me they do, I get her to note on the receipt that she's said so.
Anyway, back to your question on Doll 10. I bought the last TSV (I'm a foundation junkie!), and quite like the Hydragel. I'm usually the second lightest shade so bought the Light. I have noticed that when I put it on initially it does make my skin look a little grey and flat, but after 10 minutes, it warms up on my skin and looks quite good. Doris slaps it on quite thickly to cover imperfections. That's never worked for me. I use a damp Beautyblender on my drier areas (a must for a good finish on my skin), then either the brush in the kit, which is lovely, or one of my newer buys - a W7 knock-off of one of those high hair count paddle type brushes (amazing for blending into the open pores on my t-zone).
What shade do you think you are, LATI? In basic terms? Porcelain? Light? Medium? Tan? Dark? You can decide undertone later - unless you have a v VERY strong undertone. Basically cool undertones belong to the fairer, pinker skins and warm are more touched by the sun. Are you more Nicole Kidman (obviously cool) or Jennifer Lopez (not so obvious as her shade is darker). It can be very confusing as there's a tendancy to go warmer with darker shades (quite a good thing sometimes - check out the darker models on Q. Many products will make them look "ashy" or grey and they look healthier, if not as polished in their befores).
If you hit the shops and can try any of the Garnier BB's and think Light suits you, then I'd say Light might be your best bet in Doll 10.
Hope this long and confusing post helps a teeny bit.
