To carry on with Ken's post, what is important is to be seen, day or night. The colors of your clothing and equipment can help. Large signals can be made on the ground with your colorful gear. If using natural materials think color, contrast and shadow. You can construct signals using things that stand out from the area where you are making your signal. Letters in the sand will work if the provide enough of a shadow. Dig and pile up the sand to construct your signal. Size does matter here.

If you are carrying some camping gear or survival gear, choose the things that can be used for signals. Emergency blankets pack small and expand to a fairly large size, more than one is even better. Sleeping bags, tents, sleeping pads, etc., can all be placed end to end to build a large signal.

For the strobe, I tend to use the military issue Military Distress Marker .

Remove the IR cover and it works well, is light and small. The ACR PLB that I have includes a strobe light when activated.