Since it's winter, it stands to reason that your baby's skin is going to be a little dry. This link suggests cutting back on bath time, making sure the water isn't too hot, and limiting the amount of contact your child has with soap. Baths strip the natural oils off the skin so you don't want to over-do the number of baths she gets or how long she's in the tub.
It also suggests moisturizing immediately after bathing as your skin will absorb the lotion better, and that the general rule-of-thumb with moisturizer is the thicker the better. If Johnson's isn't working, you might switch to a thicker lotion or a cream instead of Johnson's which is pretty thin as lotions go. Some of my mommy friends have had good results with Cetaphil or anything that's unscented and/or hypoallergenic.
- Use a humidifier.
- Don't let salt or chlorine dry on the skin. In case you visit a local pool or something.
- Protect your baby's skin from the elements. Make sure when you take her out that she's thoroughly covered and protected from the wind and cold.
ETA: As for her dandruff: She probably has cradle cap which is an incredibly common condition. Both my kids had it. It's really hard to get rid of altogether, but you can sort of minimize it. When I washed my kid's hair, I would take a really soft baby brush and sort of massage their scalp in circular motions while the shampoo was still in their hair. This will help loosen some of the dry skin and you can just rinse it away. It probably won't get rid of it 100%, but it should help. I've also heard you can use olive oil to do this, and once I got really desperate and used a combination of shampoo and baby oil on my daughter's scalp, but it took FOREVER to get all the oil out of her hair. There are also some cradle cap shampoos you can buy at any big box store if some of the home remedies don't help. If it's REALLY bad and none of this helps, then you should probably talk to your doctor about it.