What part of the world and what time of year?

In general, you want to prioritize rescue over acquiring food and water. A set of three markers in a triangle that can be seen from above is a universal sign that someone needs help. Flashing mirror at any passing aircraft is also good.

For food, don't worry about it until after you secure water and shelter. It takes well over a week to starve. Water, boiling is best; you can do this even without a pot by heating rocks in a fire and dropping them into a basin you've filled with fresh water. Failing that, fast-moving streams are somewhat less likely to have as many parasites and dangerous microbes. But boiling is best!

For shelter, building a lean-to with fallen wood against a big rock will do for your first night; break off leafy branches and layer them over top to shed water. Longer-term, big sheaves of long grass bundled and stacked will insulate and shed water better.