If  you found yourself  washed  up on  a  deserted tropical island with no hope for immediate rescue, what  would  you do?
The immediate first step is to ensure you are not materially injured.  Assuming your only manifestation of harm is a psychological roller coaster of fear, anger and hopelessness,  your best course of action is to attend to your basic needs first.  

Locate a protected space away from the wind but not too deep into the surrounding jungle, built a fire pit and gather enough combustable materials to carry  you  through  the first few evenings.  Find fresh  water and someway to hold it (open coconut shells / fashioned palm leave bowls etc) - DO NOT DRINK IT until you boil it first over your new  fire so you mitigate the risk of getting sick.  Before your first nightfall with secure fire and water taken care of, build yourself a  make shift shelter so you  are protected from the elements and yet  to be discovered critters.  

Day two, focus your  energies  gathering food  (coconuts / seaweed / clams etc) so you keep your energy high.  Once your very basic needs are met (shelter / water / food to survive), its  time to fashion a fishing pole and a sharp spear out of bamboo so you can fish  and hunt for birds to expand your  food sources.  

Day  three, focus  your energy on building yourself a more permanent shelter.   Explore the island for  wood and rock sources; along with large palm leave you  can fashion rope from.  While exploring your  new home, look for caves and / or places  where you could construct a tree fort so you can improve your protected living space.

Week 2, once your new living  quarters are secured and you have sustainable methods to care for your basic needs, climb to the highest point of the island and look for nearby islands / land and any indication of human habitation.  While searching for these indicators, assess methods of island escape to get through any surf  and start tracking wind and weather patterns daily so you can get a feel for the seasonal rotations.

Week 3 +, dedicate 3-4 hours a day to building signal fires and SOS stone messages that overheard planes may be able to detect.  It is also important  to manage your mental health and track daily changes so you keep your sanity in check  as you adjust  to the new reality.

Create a way to chronicle your experiences.  One day you  will escape your island and can sell your story to Hollywood.  Of course, if you  never do escape, you will  at  least  have the comfort of leaving something behind for eventual discovery of proof you did survive the incident that landed you on this island.