To visit Nubra Valley, Pangong Tso, Dha Hanu, Tso Moriri and the Upper Indus (beyond Upshi) foreigners require a permit (Indian citizens simply fill in a self-declaration form). Applications must be processed through an approved travel agency, though in 2016 it was possible to start the process online. One minor hitch, for single travellers, is that there must be at least two applicants at the time of application, but agencies can usually fudge this and once you have the permit, travelling alone seems – for now at least – perfectly OK.
Applications must be made before 6pm (or 4pm Sunday) to be valid for next day use, but it's wise to leave a couple of hours' leeway. Before departure, it's a good idea to make several extra copies of your permit.
Permits are valid for up to seven days. On top of the variable agency fee (typically ₹150 to ₹200), the permit cost is composed of three elements: a ₹100 Red Cross contribution; a ₹20 per day 'wildlife fee' (not required for Dha Hanu permits); and a ₹300 ecological tax. The ecological tax is valid for a year, so you won't pay it a second time if you later require another permit, assuming you apply with the same agency.
Foreigners are not generally allowed to visit Hanle village nor to drive the road between Pangong and Tso Moriri via Chushul, Loma and Mahe. For Indian citizens the situation seems to vary year by year; at the time of research, Hanle permits were being given fairly easily by the DCO in Leh in less than an hour.