Hello! I plan to be in Yunnan in February this coming year. I have visited (eastern) China during the Lunar Festival on one previous occasion where i heeded advice and pre booked all my trains upon arrival in the country, then was surprised to discover them all relitively empty. This time around as my itinerary does not particularly follow the train lines (Xichang, Lugu Lake, Lijiang, Shangri La, Dali, Kunming ) what can I expect to experience by relying on bus travel considering the weather and festivities of this time of year? or am I being completely naive? (Obviously I hope to prebook a train for the dali - kunming leg) Open to any advice or suggestions, thanks in advance!

Avoid night buses if they exist on routes due to safety issues. Plan to depart most locations first thing in the morning when bus options are maximum....and on some routes, the only departure times. Try to buy your ticket for the next onward segment 1 or 2 days in advance if possible. Depending on which days during Chinese New Year you are actually traveling, buses might be extremely in demand or not much more than normal, on many of these routes. Hard to say. On major routes, often increased demand will be met by adding extra buses. There is always the creative backup method of hitching a ride with a car heading in your direction--but takes some Mandarin skills to pull off.
Buses are hit and miss, but remember that bus fares are traditionally increased quite a bit during CNY.
I would not suggest hitchhiking. You need to get to the right spot for your destination on the far outskirts of the city, and will be left off in a similarly remote spot..And you'll be expected to offer about the equivalent of the bus fare.