What better place to start than the opening theme of the series?
(You can see a youtube video of it here)
Of course in the credits Jessica is seen only fleetingly and her outfits are not clearly identifiable, but I gave it a go, just as a warm-up!
Jessica on the bicycle is wearing comfy and (I bet) warm clothes:
The white shirt is very simple, a staple in any wardrobe. I found one at H&M for £12.99 which has a very similar collar to the one which JF is wearing.
For the jumper (or jacket?) it was a bit more difficult to find something matching, however I think this fleece jacket by Mountain Hardwear is somehow an adequate compromise.
The black trousers are again another staple item, and these by H&M at £14.99 are a great and easy choice.
For the white sneakers, there are plenty of choices, often very cheap. I chose a more pricey pair just because I liked their shape, but I am sure any other would be just as good. These are from DKNY and currently on sale.