My must-have winter items are nothing in particular. My must-have winter items are nothing in particular.

This is ok, but I feel it would be more natural to say something like "I don't have any particular must-have winter items."

I don't wear many clothes int the first place, because I am resistant to the cold. I don't wear many clothes in the first place, because I am resistant to the cold.

I don't wear many clothes int the first place because I am resistant to the cold. I don't wear many clothes in the first place because I am resistant to the cold.

But I've caredbeen caring more about moistureizing recently, so moisturizer might to be myone of my must-have winter items. But I've been caring more about moisturizing recently, so moisturizer might to be one of my must-have winter items.

But I've cared about moisturemy skin has been dry recently, so moisturizer might to be my must-have winter items. But my skin has been dry recently, so moisturizer might be my must-have winter item.

I think this might be a better way to say what you mean.