Hi Umair Munawar You can start with thinking of a landform you wanna experience .It can be Beaches, Mountains, Tropical Forest(Jungle Safari).And then choose a way to reach there by flight if too far or by Railways. Then make a budget which mainly include food, shelter and transit cost. It's almost done you're ready for a trip.
Trip to Manali
How to make budget
Transit Rail You can get info in IRCTC website.
Bus you can google it or use Redbus.
Flight Google Pvt taxi use ola outstation
For Food use Google maps for average prices.
Hotels use OYO or google maps.
For trips use TripAdvisor.
Hope you like it