Beyond the learning by trial and error (and lots of time) thoughts (certainly true enough and good advice), there are also some plugins out there that can make it easier to get something useful without having mastered all the ins and outs. I’m specifically thinking of plugins that both provide some starting point presets for an entire vocal chain and which provide controls that are more “quality-oriented” as opposed to “technically oriented”. So, for example, instead of adjusting reverb pre-delay times, EQ frequencies and Q settings, and so on, you might be adjusting a “more/less” (of some specific control slider and choosing between some quality-oriented buttons for that control (e.g. tight/large/chamber for reverb types, bite/top/roof for a “treble” control for EQ). In essence, you’re experimenting at a more macro level, and, of course, using your ears to decide what you like, to see if you can home in on a sound.
While there may be other plugin developers that have similar plugins, the ones that come immediately to mind for me are the Waves “Signature Series” vocals plugins, such as CLA (Chris Lord-Alge) Vocals, (Tony) Maserati VX1, Eddie Kramer Vocal Channel, and JJP (Jack Joseph Puig) Vocals. (While Waves also has Butch Vig Vocals, that one doesn’t include delay and reverb in the areas it covers. They may also have some others I’m forgetting – the ones I mentioned were specifically included in their Signature Series Vocals bundle. The Greg Wells Vocal plugin does incorporate delay and reverb, but is way more limited in its controls, though it can also provide instant gratification for some voices and genres.)
These plugins don’t necessarily provide instant gratification, but they can sometimes provide a less stressful way to try and get a sound quickly if normal EQ, compressor, deesser, saturator, delay, reverb, etc. controls are overwhelming. One downside, though, would be that using them won’t provide the same sort of learning experience that duking it out with more basic plugins would provide. But perhaps trying to get something more quickly that is satisfactory for current projects could be beneficial while trying to learn in parallel. And some of the plugins’ high-level descriptions might provide some conceptual ideas to help for learning more basic plugins (e.g. what is the difference in sound between the reverb types?).
To be honest, I’ve only rarely ended up using these plugins in my finished projects, but I tend to use them a fair bit to get a vocal sound that is “in the ballpark” while comping vocals. Then I’ll (usually) go back and start from scratch with different plugins at mix time. But there have been a few times here and there where I’ve really liked what I was getting from one of these plugins (especially the Greg Wells and Butch Vig plugins, albeit adding my own additional plugins in the latter case to handle ambience), so ended up using them in the finished project. (I think I’ve also used the CLA plugin on a background vocals submix a few times.)
Mind you, I’ve been working on my recordings since long before these sorts of plugins existed, but they can sometimes provide nice shortcuts in a pinch, and I also find that every song is different, so putting together my own presets for plugins I’ll more likely use doesn’t help much.