From most places in California, the easiest route to Pinecrest Lake is to take Highway 99 to either Highway 108 or Highway 120 and follow one of them east. When they merge, stick to Highway 108 through Sonora and 30 more miles up to Pinecrest Lake.
From Eastern California or Nevada you may consider coming west over Sonora Pass (Highway 108). It is not recommended for large motor homes or for vehicles pulling heavy trailers. Highway 108 leaves Highway 395 at Sonora Junction.