I love dressing for colder weather, because you can find lots of modest clothes in shops around Winter time. Have a look at some of my older posts including Winter wardrobe essentials, and the cosy cardigan outfit. I love wearing long cardigans to keep warm.
The key to keeping away the chills is wearing lots of layers. This also allows you to remove some of your outwear for when you are indoors, and it's not so cold. Use a pretty pashmina as a hijab, and don't forget legwarmers, scarves and gloves:
Pashmina, H&M; black knitted tunic £35, Oli; long sleeved t-shirt £7, Dorothy Perkins; black and white coat £30, Debenhams; chunky wrap cardigan £12, ASOS; bootcut jeans £25, Dorothy Perkins; leather gloves £15, Dorothy Perkins; frame bag £15, Wallis; high-leg boots £70, Barratts.
I hope this outfit has given you some ideas of how to dress for colder weather. I've used neutral colours only here, so you could always add something to brighten it up!