Methods for palette coding of image and video data to avoid issues associated with zero-size palette or to improve performance by conditionally signaling CU (coding unit)-level escape pixel presence flag are disclosed. In one embodiment, size information related to palette size of a current palette table of the current CU is signaled conditionally based on the escape indication flag, where the escape indication flag indicates whether there is any sample in the current CU coded as an escape pixel. In another embodiment, the CU-level escape pixel presence flag is conditionally signaled according to the current palette size or both of the predicted palette size and the new palette size. Conditionally signaling the palette sharing flag may also be based on the palette sharing flag.