1. Repeat the last action
you may already do about the shift + r short cut for repeating the last action, what you may not know is that it also works for rotation and scaling.
when you duplicate an object multiple times while slightly rotating the object, just escape out of grab/move mode by using R for rotation or S for scaling and when you confirm the action with left mouse, you can repeat that action by using Shift + R|
2. Any surface can be a pivot point
when you want to rotate objects, shift + right click to move the 3d cursor to any surface, use the period key/ full stop to access the pivot point pie menu to change the pivot point to 3d cursor and now when you rotate the object, your 3d cursor location will always be the pivot point, and you can snap the 3d cursor to any surface in your world.
3. Access your project folder
if you are in the file browser and you need to access your project folder, just use // in the path input and it will navigate you to your current folder, this only work if the project is saved otherwise blender will direct you to your documents folder or desktop
4. Speed up your world building with collection instances
if you are working on large scenes or even small scenes with multiple objects in different areas, you can group these objects into a collection, that you can add into your scene multiple times as a collection instance, every collection you have in your scene can be readded into your scene as a collection instance, use Shift + A to access all your collections as instances, this also helps in optimizing your project as instances dont require as much computation power as other objects so you can add as many as you want.
5. take advantage of viewport rendering.
when working with animation a slow lagging viewport can throw your timing of, everytime you try playing back in the viewport, the animation will play slower than the intended fps, you can use viewport rendering which renders really fast especially if your are using solid mode, which renders without any shaders or lights.
Note: your animation will be rendered out using your output settings, and will be saved in the output folder you selected, if you have any previously rendered animation in that folder, it will likely be overwritten
6. use game navigation WASD
if you have a large scene you want to explore, wasd keys can be used to navigate your world similar to what you do in video games .
you can use E to move up, and Q to move down, mouse will to increase navigation speed
7. Rendering glass
ever tried rendering glass but it does not look the way you want, add a solidify modifier and see the difference.
left has no solidify modifier so its rendered as its all glass, right has a solidify modifier so its rendered as a glass shell, the thickness value of the solidify modifier is used todetermine the thickness of the glass
8 reduce texture tiling using mirror option
textures sizes are not infinite but surfaces can be nearly infinite or larger than textures, to make sure the entire surface is covered even when you have a small texture, you can extend the texture by tilling it, the issue is, texture tilling does not look good, if you want a quick fix use the mirror option to extend the texture tilled but mirrored in all directions.
9 hair particle correct rotation
if you have particles and the render setting is set to object, but cannot get the particles to rotate the right direction and you want a quick dirty trick to correct the rotation!
select the particle object and try rotating it in edit mode until you find the right rotation.
10 create a pile of junk
if you want to make a pile of junk easily, use the rigid body system, you can add a number of objects give them rigid body physics and simulate them falling into something shaped like a bowel so they are collected together like junk, then remove bowel and apply the rigid body physics to the objects.