Baijnath, Palampur and Dharamshala are popular starting points. From here you go over the Dhaula Dhar at passes such as the Indrahar and Minkiani both from Dharamshala and the Waru from Palampur, then enter a feeder of the Upper Ravi Valley. A good trip which includes the upper part of this valley is the round trip trek from Manali.
Midway up the valley, which lies between the Manimahesh Dhar and Dhaula Dhar ranges, is Bara Bangahal. From there you can go downstream to Chamba or upstream which offers the choice of at least three passes for crossing into the Kullu Valley. The northernmost of these is the Solang Pass which passes Beas Kund beneath Hanuman Tibba. In the middle is the Manali Pass whilst the southernmost is Sagar Pass.