It is also very important that the side and mid components sound great in isolation. When multiple elements sound great in isolation, the whole is great sounding, so check as many elements as possible in solo and improve the sound. I also think hardware stereo processing is a must have, as well as various warmth adding hardware. It takes a bunch of gear before you have a big warm well separated sound...[/
When you say Side and mid components what are you referring to, what are the components? And is this hardware stereo processing and other hardware, the same as the plugins in my DAW?
M/S processing.
Getting a good stereo image is this process of combining certain signal routing + panning with a mix of various stereo enhancing hardware effects active relative to the short term and long term dynamics at various scopes of application (individual track, group, mix) while also maximizing the total amount of resonance present in the mix through amplification, balanced in a truthful monitoring situation. This you can sense as the mix having a certain amount of stereo resonance. When you work with the elements in the mix you make various elements "big" sounding and this makes up an overall fat stereo image. You need certain hardware...
There are many routes you can take, but a great mix has to have great M/S performance. Lots of mixes out there have congested dynamics, noise and muddy modulation in the S component. It tends to make mixes quite bad sounding. So you should ensure you have great M/S performance.