I think Bobbi Brown make up artists are really well trained. And they will fill out a little card with a picture of a face on it, marking the different products they have used and where, which I think is really nice, because it takes the pressure off you to buy then and there.
I would second the advice from others OP, no one make up brand has all the best products - go to a big department store at a quiet time (weekday morning) if you can, when sales assistants are well rested (seriously!) and have time on their hands to spend with you, and I would personally go into it telling myself I wouldn't put any pressure on myself to buy. Try lots of different things, then have a think about what would fit best with your lifestyle.
All that said, I think you should be looking for a great concealer to use on any reddish or dark areas, eg around the nose - NARS have a new cream concealer out that is lovely. A foundation, tinted moisturiser and/or powder for some coverage, depending on your preference. YSL Teint Eclat is great, By Terry does a clicky brush of liquid foundation that's brilliant to use, lots of people also love Bobbi Brown. New killer BB creams include Dior and Givenchy. You also need a lovely powder blush, a decent mascara (consider brown or brown/black, true black can be harsh), and a good nude lip, by which I mean something not a million miles from your natural shade, but gives your lips definition and plumpness and some colour - not one of those horrid plasticky skin coloured caramels! Those five products may take some time to find, but the right ones will be a joy to use! And then if you're enjoying experimenting, you can mix it up with coloured liners, shadows, bright lips.
You might also look back at some Sali Hughes columns in the Guardian, though I don't always agree with her recommendations, she is good at guiding people on what you should be thinking about when you're looking for products.
Have fun!