In this guide you can find a basic info, which will help you to get on your way and streamline your experience, if you so wish. It will not include an in-depth bait to fish spreadsheet.
Hit F1 to see basic controls.
E to access shops. aka The Van, The Store, The Tent, The Car.
Fish can be everywhere. But that does not mean they are there every moment. They move around. If you're not getting bites, you're probably doing something wrong for that spot. Change around baits, gear. If all else fails, move.
Quests (Q) are the single most important thing for you to focus on, if you're looking to progress at a decent pace. Find an area you like, see what fish you can catch on the best rate, then choose quests accordingly. You can start knocking these out pretty fast. You can cancel a quest by holding alt, then right clicking on the quest top right.
In the beginning, Large Crucians are your money fish. If you find a spot where you're catching them at a decent pace, keep going. Write it down so you can come back.
The game follows a loose rule of thumb and logic for fishing. Smaller baitfish will mostly be closer to shore. Some fish prefer reeds. Some fish prefer lilies. Some fish prefer deep water, some prefer medium water. Some prefer narrow water, some prefer wide open water.
For example: Pike are roaming predators. They prefer coastlines, especially along reeds, fallen logs, trees. They don't have the greatest vision, so they tend to be more active 9:00 to 16:00 then tail off at night. Perch are similar, being VERY active when the Sun rises, then tapering off as the Pike start roaming.
Zanders are the opposite. They have no wish to be out during the day, and only roam when it is completely dark.
Catfish are lazy gluttons that just want to be left alone. They find spots in deep, dark holes, then eat anything that comes close to their mouths (though in this game, they are slightly more picky as of now). At night time, they become more active, often creeping out of their holes to feed in the shallows.
If you look at the water, you will see little ripples everywhere. While I can't 100% confirm it, casting at these seems to increase bite rate, especially with floats.
Hook size is pretty important. The smaller the hook, the more bites you will get. The larger the hook, less bites you will get as there are less large mouths for that hook.
The smaller the hook compared to the size of the mouth attacking will determine the chance of "fish got away". But this is pretty rare and you don't have to worry too much about that for a while. I would not go above size 1 til you are much higher level.