4 days in Guilin

Oh, four days are enough for you to tour around. The suggested itinerary is the following:
Day 1: Fubo Hill, Seven Stars Park, Zhengyang Pedestrian Street
Day 2: Reed Flute Cave, Elephant Trunk Hill
Day 3: Li River Cruise, Impression Sanjie Liu Show in Yangshuo
Day 4: Yangshuo West Street, Ten-Mile Gallery (Shili Hualang) by bike

Do you wanna go there in January? If yes, the forecast shows that the temperature will be 45 F to 55 F. It will be a little bit cold. Some showers won't influence the sightseeing a lot. About the clothes, you can prepare jackets, thin sweaters, long johns and pants.
Have fun!

Is it nice to visit the dragons rice terrace in January? And do u know if tickets have half prices for students? Thanks for you help

Well, you will see the rice field full of water in January, nice for photography. As I know, the concessionary tickets are applicable to Chinese people only. Sorry for that. :)