Let me start with a disclaimer: I play the console versions. I only played the computer version once, so if any of these are not correct cross-platform, please indulge me. These are for the Console Version (PS4 flavor).
Any feedback, refutes, or (especially) suggestions to improve these are welcome!
1. When you find a village, build "door" structures until you get 15-20 villagers. Wall up the village. Then start digging trenches nearby and filling them with water and planting sugarcane. Tons of em, so you can harvest 6-10 stacks of 64 each time. After harvesting, turn it into paper. Now trade with Librarians for Paper for Emeralds. In fact, kill off any villager not selling for Paper (they will respawn until you get the ones you want, just be careful of golems). This way you will get tons and tons of emeralds.
2. Buy nametags with Emeralds. They are the only goods sold by villagers that you cannot produce on your own.
3. When harvesting sugarcane, run through the row, hitting at the second block. This way you never have to replant, making harvesting a snap.
4. When building a pen, here's a way to be sure the animals don't leave when you do... go to the corner of the pen, dig a 1x1 hole about 6 deep. Put a sign inside the shaft and then put water over it. When you want to leave, fall through the hole. Creatures can't follow, they will just swim.
5. Need eggs? Fence in a chicken. Then fill in the ground of the pen with hoppers. Now you'll endlessly get eggs that will not despawn.
6. If you have a large tower/castle, consider making one long continuous shaft that goes through the whole thing, with water at the bottom. And access doors on every level. Fill the bottom with water. Now when you want to get to the ground quickly, just fall down the shaft.
7. Cure zombie villagers only if you need to repopulate a village up from 0 or 1. Otherwise, you're better off just building doors and letting the villagers spawn new citizens, without wasting a gold apple.
8. Set up a "hunting ground." A flat area near your base... line it with cobblestone. Now, at night, you can go kill monsters in an area that is flat (meaning they can't sneak up on you and they are all visible for a long distance).
9. When setting up your base as a multilevel, always put the floors you use the most lower, and the floors you use occasionally higher. For instance, I ALWAYS put my workshop at the ground floor. Spending all your time going up stairs to bypass floors you never use is annoying. Also, if you have a floor that makes noise (ie a gate, livestock, etc), consider putting that one far up, so you don't hear it around the clock.
10. Watch + frame = Instant wall clock.
11. Resetting the nether makes quartz, lava, glowstone and horse barding (when you can find it in fortresses) endlessly renewable.
12. Always carry a pile of wood with you. Not planks, wood. This way, you can create 4x the planks in the same space, when needed (you dont need a crafting table to make planks). Plus, as you'll doubtlessly have a lot of coal while underground, this means you'll rarely, if ever, run out of torches (they also don't need tables to create).
13. Not all buffs may fit your playstyle, so evaluate what's a good buff carefully. For instance, Knockback (in any form) really sucks when you're fighting skeletons -- it moves them away to get extra shots on you.
14. When the string starts to pile up in your stores, turn it into wool and trade it to villagers.
15. Rotted meat is perfect for feeding your wolves. To them, it's just as good as steak for healing power, with no ill effects.
16. Build your castle near the original spawn point. That way, you'll never be lost when you have a compass (or can build one out in the field).
17. Carry a bed when you are exploring. When the sun sets, simply dig down and carve out a small 4x4 cave. Plug up the hole. Drop a torch, then the bed. Sleep. You'll pass the night without getting hassled by monsters.
18. If you are not actively using Poisons or Weakness Potions, spider eyes are worthless. Dump them immediately once you've collected a token pile for your resource chest.
19. Skeletons will attack each other if they accidentally hit their comrade. Use this to your advantage, especially if you get caught in a multi-skelly crossfire (which can kill you pretty quickly).
20. Every floor (actually every room) of you castle needs a crafting table. For convenience. Embed it in the floor so it doesn't clutter up the place.
21. Pumpkin Pie and Steak (and possibly pork chops) is really the only viable food, in my opinion. The other stuff is strictly fluff.
22. You can fish in any water that's 3 or so deep. Just build a pool in the corner of your castle for this purpose.
23. Horses have different speeds. The speed varies, but note that two fast parents will produce a fast foal. Mark a length of road and time how long it takes you to cover it, and note it and compare it to the other horses when selecting your preferred mount. I actually keep signs in each stable with their best times.
24. If you are playing on Peaceful difficulty, don't bother with horses at all. Mules can be just as fast and they can carry a pack... you don't need the barding (and thus a horse) if there's no monsters about. Note you'll not find a mule naturally. You'll need to breed a horse and donkey to make one.
25. Build a keep around your castle, and then put golems inside the keep as patrolling guards. Make sure the exits to the keep are only two blocks high, so the golems can't exit.
26. If you're not opposed to save-scumming, then never repair an item. It's far, far, FAR cheaper to rebuild it (saving and exiting until you get what you want).
27. If you find yourself using a potion combo before heading out (to mine, to hunt), consider making a network of chests, hoppers, dispensers and pressure plates to automatically eject your potion combo into your character. Put a hopper in the floor in the corner so you can throw the empty potion bottles in there after you quaff (collect them every once in a while).
28. Low on roses and dandelions? Dig out a 5x5 area, 2 deep. Line it with cobblestone edges but be sure there's grass on the bottom. Now, on one end put a small tower with a water square up top and a piston holding it back. On the other side, line the bottom with hoppers. Now, just keep putting bonemeal on the grass, then letting the water out (and shutting it off after it wipes the batch). Keep at this for a while and then check your hoppers. Tons of flowers.
29. It's easy to get lost in the Nether. And God help you if you run out of nightsight potions and torches while lost. So build obelisks of sand (which is not native to the nether), with one sandstone block on the side pointing towards the gate's location.
30. Even if you have redstone coming out of your ears and dont want any more, mine it anyway. You can always use the experience.
And one more to grow on....
If you are (or planning to) play multiplayer, ALWAYS keep your real valuables (your main diamond stash, emeralds, ender eyes etc) in a chest buried in a nondescript location. No matter how much you trust your co-players. Better safe than sorry.
I like this list and I did work out a lot of this on my own over time, as we all do by trial and error, but it is good to see a lot of sensible stuff in one place however - #21. Pumpkin Pie and Steak (and possibly pork chops) is really the only viable food, in my opinion. The other stuff is strictly fluff.
I have to disagree, Carrots may not be as nutritious but they are the only food you do not have to cook apart from melon slices but they have way more substance, I have found it more convenient to come back to base and use carrots as a base food just by farming and not going near a furnace or crafting table, let alone using sugar and wheat. I plant carrots all over the world.