Somewhere, where you can explore, especially mountain sides. You can go to Mussorie and all the places nearby there.
If you want to travel to beaches, Pondicherry is a good option.
Anywhere within your state ,within your reach. collect all the information about the places you cud stay ,eat , explore, weather, transportation,and community around .. then plan accordingly. you didn't mention where do u live so here are some options u can consider them if you live somewhere around these places.
Rishikesh
Jaipur
Aagraa
Dharamshala masoorrie Goa
Nainital
chopta tungnath
I recently did a solo trip to Jaipur. There are several beautiful places to check out like:
City Palace Galta Ji Temple
Johri Bazaar
Nahragarh Fort
Hawa Mahal
For the first time.. a place not very far off from where you stay..there could be laods of options.. pondicherry, himachal egg.. depending in your travel interests!!
Kasol or Spiti Valley situated at Himachal Pradesh .And you will find many solo trip planners for these two locations. solo trip communities like wetravel solo, tripoto etc
Again this depends on your liking ( hills vs beaches vs historic place) , time of the year and budget. E.g. I went for my first solo trip to Cambodia in Dec 2018 You may pls go through my published blog for the details of the trip.
If you want to go for beaches, visit Pondicherry or Andaman!
In Andaman you can take part in various activities like scuba diving. Check out https://www.funstay.in/andaman-tour-packages
It depends on your liking if you are doing 1st solo trip then try to choose destinations with live events.. destination really doesn't matters but the experience is so choose it wisely and according to what kind of experience you want from that trip
Manali if you live in north, Pondicherry if you live in south, Meghalaya if you live in north east, However, finalize a destination that you really want to visit.
Go to a place which has hostel so that you can meet more solo travelers.
You can try Udaipur.
And if you want to visit mountains try Dharamsala, Bir or Tirthan.
If you are a tropical person than check varkala, Goa, gokarna etc. If you love mountains then check tosh, mcleoganj, kasol, rishikesh etc. Hampi, pondicherry, udaipur are other options
If someone really interested for its 1st solo trip then there are many places in India and in the state Odisha too. Places like Puri, Konark and other places one can visit. During the visit one can search many hotels in Bhubaneswar The HHI Bhubaneswar is one of them. Which provides better facilities at a very affordable price.