The best time to visit Himachal Pradesh is from September to November and April to June.
Tip - Never ever visit this state in the months of December & January. (Due to extreme cold climate)
You can catch some of the breath-taking views if you're planning to go in the months of April and May because the mountains are filled with snow. The captivating views of snow-clad peaks would leave you mesmerised.
Carry good sports shoes or trekking shoes that will last for years. Spend some money on buying good quality shoes so that later you won't regret.
For clothes, make sure you get woolen and hot warm material ones. Sweaters, hoodies, thermals are really important. Good track pants are too essential.
For food, you don't need to worrk because Himachal Pradesh is considered to be one of the best food-serving state's. So by any means, do not forget to pay a visit to local shops and stalls. The quality is extremely good and the price is cheap too.