Pack good with lot of woollens and spiked trekking shoes because you will be finding lot of snow there in february. If you have good prior experience you can trek solo there , its not that difficult but if you want a hassle free trek you can contact one out of lot of trekking companies there like India Hikes etc. You can also meet good travelling operators in Dehradun. They can set up a good trip for you.
Maintain your health do exercise and running approx 3 km in 30 mins. Take warm clothes , chocolates and essential things which would be provided by your trek organiser.