Though, a decent high pass filter on any channel needing some low rumble/mud removal is a great place to start, technique-wise.
I actually wish I had remembered this, because that's actually something I think
should be just standard operating procedure for anyone working on a DAW when it comes to mixing: every channel that does not need to have any bass frequencies should have an EQ or a filter that cuts off any unneeded frequencies if the sound has some. Most of your sounds, whether synth or sample, will have harmonic content in the 30-250 Hz range. If it's not a kick or a bass, any of that information is just adding to the overall volume of that frequency range, which isn't beneficial at all. Start sweeping up in frequency until the sound starts to lose a bit of its character. It'll probably start to sound a bit more hollow - that's when you know you've gone too far, and you can back it off until it sounds normal again.
Other than that, if you're just starting out think about an equalizer as a surgical instrument, not a necessary effect (even though it is, and you'll soon realize why) - you should only consider using an equalizer on something that sounds good but it doesn't
fit with everything else. All the creative design and/or advanced mixing applications are great but they can distract you from the most important experiences that a beginning producer or engineer should be developing: how to remove frequencies from specific sounds so they do not get hidden when they are played at the same time as other sounds. That was the core function of an EQ, before any sort of mid-side or sidechain or crazy sound design shaping came into play, and sometimes I think new producers (especially ones without any experience in classical sound engineering) tend to look at all the
cool stuff you can do in your mix and can overlook what the
necessary stuff to do in your mix can be.
Like I said, just listen to a lot of songs that you love inside your DAW. Dissect them and try to recreate them. Figure out how the sounds are blending together to take up the whole frequency spectrum while maintaining their individual clarity. A finished song is an open book, you just have to be patient enough to read the pages instead of watching the movie.
EDIT:
1. EQ // get your sound clean
I actually want to kinda clarify on this a bit, because I think this wording is what leads to a lot of bad habits for newer producers. We should be careful not to conflate "clean" with "good" - you don't want to EQ a bad sound to make it a good sound. You want to EQ a good sound to make it a
better sound in the context of your mix. Sample selection and sound selection is a critical skill to develop, but it is something that is hard to understand at first. That's why I recommend learning drum programming and sound design before you start approaching the concepts of mixing, because by learning how to create your own drum kits and your own loops you will start to hunt for samples that sound more like the loops you have or the tracks you are taking loops from, and by learning sound design your taste for synthesizer patches improves.
You want to learn how to do everything, but you don't have to learn how to do everything at once.
