Explore Islands
Spend your first 8-10 days exploring, when you find new islands make a not of hard-to-find resources that are there like gold and spiders.
Making Camp
When you are looking for an island to put down camp choose one that has at least a beach and jungle biomes and if possible a couple more. It is important that you have several biomes because a lot of plantable things can't be placed in certain biomes.
Hunting Whales
To get loot from Whales they need to rot 3-5 days after you kill them and because they only rot when you are close by they are not worth hunting unless you can spend that long at sea.
Chopping Trees
When chopping trees for the first time favour Coconuts over Jungle trees. This is because the fronds from the Coconut can be used for Thatch Sail and Thatchpack. The Jungle tree can spawn snakes which will just slow you down when you don't have a spear yet.
Shaking Bushes
When you encounter viney bushes that shake you need to hack at your own discretion as they contain snakes.
Dodge Waves
Become proficient at dodging waves because hitting waves damages your boat and forces you to build a new one early which will mean wasting valuable time collecting resources for. Hitting waves will also get you wet which decreases your sanity.
Monkeys
Monkeys will try to steal items from you so it is in your best interests to keep them away from you.
Crabbits
Make sure you do not leave food lying around as Crabbits will eat food left on the ground.
Prepare For Hurricane Season
Make sure you explore as much as you can in the first 15-20 days before hurricane season arrives. During this period of time you will have more day time and no constant hazards to contend with like high winds and lightning strikes.
Full Moon
Don't build alchemy machines or anything electrical near water because on a full moon the water will rise and destroys the machine.
Craft a Torch
Make sure the first thing you do when you find an island is craft a torch. If you don't do this you have doomed yourself to failure as Charile will get you when it gets dark.
Early Healing
A good healing/food early in the game is 3x crab meat and 1x berries in a cooking pot.
Preparing for Spring
Make a lot of sandbags because they will prevent flooding. Also having an umbrella is a good idea too.
Trawling Net
The trawling net is one use only, don't unequip it unless you know it's full.
Forest Fires
Only you can prevent forest fires by being careful with torches and campfire placement.