Individual Track: Raise the volume, Raise the Waveform dB, or compress?

[triple_seven]

Ive always had this question ever since i started with production:

What is the right way to raise the volume on an individual instrument track?:

1. Raise the Waveform's individual decibel level, for a larger Waveform image/sound, or
(If this was the case then do i just click and drag the waveform up and down for a large image? well atleast thats what my DAW allows me to do, click and adjust simply, or apply a mixtool plugin to adjust gain)

2. Raise the volume levels on the mixer.

3. Compress/limit/maximize etc anything that needs to be louder

Also, i've heard that gain and volume are two different things....

 

[bandcoach]

all three will work

however best sequence is as follows

raise mixer faders for each channel and adjust channel trim gain if needed
compress/etc
external normalise

gain is the increasing of a level by a specific amount of relative db

volume is the perception of a sound and is subject to the non-linear nature of the ear and its sensitivity to different frequencies at different spl's - at all levels there is a difference between the perception o of low freqs and high freqs compared to mid freqs: the higher the spl, the larger this difference is