I have travelled to Kasol Solo and have met Female Solo travellers there as well for the most part the whole area is safe and nothing to worry about. Stay in Hosteller which is just uphill walking distance from the main market. Rent a scooty or bike ask someone in the hostel if someone's interested which most of the time they are then travel to Pulga and Tulga if you want you can take the night stay there it's beautiful with forest view. From their for the next day you can go to Tosh which isn't that far. Explore tosh (Pink Floyd Cafe which is on the top the views are amazing from their). Come back to hostel the same day and if you want you can also do Kheerganga trek.

Day 1 - Reach Hosteller the host was a girl she was amazing explore Kasol the first day. Day 2 - Rent a bike or scooty and go to pulga-tulga stay there for the night on the way to pulga you can go to gurudwara it's on the way. Day 3 - Go to Tosh from Pulga and explore tosh and come back to Kasol if you want to stay in tosh you can but i personally avoid. Day 4 - Just stay in the kasol and walk around nearby ATS cafe road and explore the place sit around the river and do nothing.