Never mix fluids if you do not understand its chemistry! People have died and worse from e.g. toxic fumes and spontaneous ignition!

Get a can of liquid air to blow away dust, fluids or other stuff (pro tip: get a compressor)
Get isopropyl alcohol for cleaning PCBs. You might also like fixing joysticks, analog sticks, encoders with isopropanol and air.
Get brake cleaner to remove any grease (can also be used to clean PCBs).
Both isopropyl and brake cleaner work good on removing sweating of plastics, acetone will remove sticky velour paint.
Acetone vs isopropyl + if you don't have acetone, check if your nail polish remover contains some

Get chain-cleaner for your bike, which is basically a solvent and some oil (still needs greasing afterwards!).

Only use contact-spray if needed, better try isopropyl first! (actually, I have never used contact spray in my life, always isopropyl)

Air-in-a-can: Air is a fluid if compressed. It can be bought in cans: better get a compressor for multi-purposes and waste reduction.

Use vinegar or citric acid as a descaler to dissolve limescale - NO scrubbing!
vinegar vs citric acid

Citric acid is used in so called “bath bombs”, reacting with baking soda.

For solvents read the glue section