This is a shameful paste from some fast tips I gave on ResetEra. Hope it helps to get started.
Keep in mind that despite the 'casual' approach the game gets super deep (and super difficult).
General Kingdom tips (keep in mind I made it to the last island but I never fully completed it, so people much better than me can chime in).
Also, these tips are really generic because the real strength of the game is discovering things by your own, notably what does what and how to cope with invasion.
General tips for first island.
1) You need to survive...to do so you must build during the day and reinforce your settlements, because you can be sure it will attacked by night.
2) First island is easy...you will be attacked by one side only....so your first thing to do is understanding from where....explore both sides of the island and see where the black portal is.
As the horse fatigues you can't really explore both sides in one day, so if you don't see any portal and you are already at the coast, the attack will be from the other side.
If you leave the horse on green grass, he recovers much faster.
3) Reinforce walls for the said side. Hire archers and builders, upgrade your castle to be able to build walls.
4) Don't waste money. Collect money from chests (should be 2 in the island somewhere) and start recruiting people, possibile the far ones.
5) build some bows and some hammers.
6) archers shoot at rabbits and deers during the day, they can drop money out of it
7) your main gold income at the start is the merchant. Collect money at the start of the day and give him 1 gold so he can travel to his home to bring more gold. Next day he will be back with more money. Rinse and repeat. BE SURE NOT TO DESTROY HIS HUT IN THE WOODS.
8) There should be a temple somewhere, if you 'power' it with gold, your archers are more efficient. Effect lasts for a day.
9) Main goal, once you are 'safe'....is to have many builders rebuild the boat that should be somewhere.
10) That's it....this is only scratching the surface, many more things come later...from fields, mills, to knights, stone walls, castles and better horses and so on. Of course more enemies.
When you see the red moon, pray.