That dependent on the application type, basic decoupling -
0.1uF ceramic capacitor between every IC supply pin to ground
For noisy and high speed ICs such as microcontrollers you can add 1nF ceramic capacitor parallel to the 0.1uF
A 100nF for each power pin of each IC is a commonly accepted value. For more serious applications, you can also parallel multiple capacitors based on their resonant frequency.