Out of Fresno go east on Highway 180 - Kings Canyon Road. At Academy Ave. go north a short distance to Belmont and then follow it east. Belmont becomes East Trimmer Springs Road which leads directly to Pine Flat Lake.
From Visalia follow County Highway J19 or Highway 62 north. A good map or GPS would be more helpful finding your way than written directions. A variety of combinations of roads will connect you to Trimmer Springs Road.