The thing with automation is that the technical side of how to do it is actually really simple (unless you want to do some really wacky stuff ofcourse). The skill lies in how creative you can get with it. The idea behind automation is that you can make certain tweaks to your mix that occur at a certain point of the timeline, as opposed to being carved in stone. So literally any choice you could make for a mix could also be applied with automation. Some musicstyles rely heavily upon it for creating the flow of the song. A good example is Levels by Avicii. Pretty much just a simple beat with a synth on top, but listen to the individual elements in that song and notice how they are constantly changing in some way or another. Volume, panning, moving highpasses, changing reverb/dry levels, sidechain-compression from inaudible kickdrums, you name it. Even if you aren't into that music style, I think it's worth checking out if you want to get some creative ideas for possible automations. To the practical side: I don't know what DAW you use, but I use Reaper, so I'll give you a simple example from that perspective. I'm sure it won't be very different for other DAWs. -Let's say I have a dry vocal track that says "And now for some delay". If you just slap delay on that track, or send the track to a delay-bus, the delay will always be active. But I don't want that. I want the delay to only work on the word "delay". -This is where automation comes in. Start by setting up the delay like you usually would. In my case, I like to use a separate delay-bus, and I send my vocals there. -Okay, delay has been set up and I like the way it sounds. Time for automation! I click the automation-button on the track I want to work with (in this case, the vocaltrack). In reaper, this is a small button on the track, called "env" (for envelope). When I click that button, I get a list of possible things to automate. Standard options will usually include stuff like volume, panning, volume and panning pre-fx (very useful!), and also send-volume/panning/mute if you have a send setup. It should also include effects you have set up on that track, in case you want to automate those. -In our example here, "send mute" is what I am looking for. What I want to do technically, is to only send signal from the vocaltrack to the delaybus when the word "delay" is spoken. So I check the box next to "send mute", and now a bar is created under my vocaltrack. -This bar is a graphical indication of changes occuring over time. I can create points on it, and "draw" a line of how I want things to change. If I wanted to increase the volume at a certain point of the song, I would draw an upward curve at that point, and it would have the same effect as if I was manually moving the volumefader at that point. In our example, it is even simpler though. I want the sendlevel to be completely mute until the word "delay" is spoken, and after that I want it to be muted again. So: -I am going to draw this on the bar. I will create points before and after the word "delay" on this line, which will function as region-markers. Wherever I want the send to be muted, I will drag the bar all the way down, and where I want the send to be active I drag it all the way up. It's pretty much an on/off-switch. Since I created a point before and after the word "delay", I can drag the bar all the way up there, without influencing the rest of the mix, and vice versa. -Now listen back to the result. The delay should only become active at the point you wished for, and remain mute for the rest of the mix. The nice part is that the delaybus itself doesn't become muted once the send stops. It just trails off like it usually would. So it could still be trailing off by the time the vocaltrack is already doing something else, and it wouldn't be influenced by it. -People have mentioned that they prefer to copy a certain part of an instrument, put it on a different track, and put the effect on that track. As long as this has the same outcome, it doesn't matter what you pick. Both work just fine. I prefer to use automation the way I do, because I like to keep my amount of tracks to a minimum. Also, fluent changes in a mix, like a moving EQ-band or changes in reverb-wetness are very easy to do with it once you get used to it. Ofcourse, this was just a very basic example of what can be done with automation, and how it can be done. You can really go nuts on it if you wish. Also, many people like having a hands-on feel to their automation, so they actually record their manual changes to an element over time to get that real feel. I wanted to keep this explanation simple though, so I won't get into that. Just keep this in mind: with the availability of automation, you don't have to make compromises in your mixchoices, as long as you aren't lazy about it! Don't let your bass sound sucky in the chorus, because it sounds good with those settings in the intro. Now you can have your cake and eat it too.