Open source modular synth software lets you create 70s & 80s electronic music

In my opinion, though, subtractive synthesis is the easiest to "get".

Starting with a relatively simple subtractive software synth that uses primitive "analog" waveforms -- like, say, Tal-Uno-62 (https://tal-software.com/products/tal-u-no-62) -- is probably the best way to play around with learning synthesis. It's a lot harder to create a "bad" sound in a simple subtractive synth, and in something like Tal-Uno-62, there aren't a whole lot of possibly confusing menu options and buttons.

Samples and wavetable synthesis are also relatively easy to get a "good" sound of quickly. Most are structured, architecture wise like a subtractive synthesizer, you just replace the primitive waveform with either a sample, or a bank of digital waveforms.

FM and additive (and spectral and granular) are neat techniques, but IMHO way more finicky to program. (They are also techniques where the software interface is quite welcome! Programming a DX sound in the (free and open source) Dexed VST is quite a bit easier to do than it is on a Yamaha DX7's two-line LCD screen and buttons.)

For the parent poster: I understand that quite a few professionals, particularly in loop / beat oriented music genres (such as hip hop / trap, EDM, and reggaeton) use FL Studio quite a bit! The nice thing about FL Studio is that it has a nice intuitive layout for beat-making. It's what I'd personally recommend for someone just wanting to mess with synthesizer beats. (My personal favorite is Reaper but I don't tend to write beat oriented stuff. :) )

There's also wavetable and granular synthesis. Both tend to have a more "experimental" vibe to them.

I think part of it is that you're conflating writing music with sound design. They often go hand-in-hand but are two different skills. Kind of like programming vs (video) game design. For example, you don't have to design a flute in order to play one. Unlike synthesizers, most instruments can't change (much of) their sound. Organs are probably the most versatile in that regard, but they achieve it basically through brute force. (Traditional instruments do still have quite a bit of flexibility, but it's nothing when compared to a synthesizer; e.g. a violin is very versatile, but you can't suddenly make it sound like like a flute)

For learning sound design, first pick a type of synthesis (as others have talked about). Most people start with subtractive synthesis and it is by far the most popular. So much so that bits of it overlap into other tools that focus on different forms of synthesis (e.g. lowpass filters as part of a wavetable synth). As for plugins, you can't go wrong with synth1. It's free, does more than what you'll need to start (you can just ignore knobs until you understand them), and has clear labels. Start with an initial patch (should be a basic sine wave IIRC) and build up from there.

Learn what the different components actually do to the waveform. You can't think of it like "this makes the sound more like this" since how it changes the sound depends on the rest of the parameters. This is probably why you end up "aimlessly manipulating ... knobs and switches".

For actually writing music (not just tweaking your bloop sounds), Ableton has a fantastic interactive guide [0] that takes you through everything you really need to make music. Everything else builds on top of that and is arguably unnecessary. It also includes great examples. There is also practically infinite information out there around writing music. Go get some.

While focusing on writing actual music: don't be afraid of presets. There's nothing wrong with using them, especially if you are just learning. Nothing in music is 100% original. At the end of the day, all that matters is that it sounds good (and you're not blatantly copying others' work). You can start to use your own sounds once you learn more about actual synthesis. As you start to learn more synthesis, try finding a preset that is close to the sound you want and then tweak it to your liking.

As far as DAWs, don't assume there is "one perfect DAW" for you. FL Studio might just not suit you. While all major DAWs should be able to achieve the same things, they often go about it differently. Depending heavily on how you want to work, some will be harder for you. You'll likely end up learning more than one eventually, so try out a few. Once you find one that starts to click, STOP SWITCHING. Stick to that one as long as you possibly can.

REAPER [2] is a great option for beginners since it has very generous pricing and trial. However, it's not just a "beginner DAW" -- it is fully capable professional software.

The key to making any progress learning is focus.

[1]: https://learningmusic.ableton.com/ [2]: https://www.reaper.fm/

Addendum: I mentioned learning what knobs do to the waveform, but I never explained how. There are plenty of options, but the most basic way that you can set that up right now for free is to grab REAPER, synth1, and some free oscilloscope plugin. This very basic setup will take you extremely far in learning synthesis.

Syntorial, while not cheap, is an amazing tutorial.

Bingo! VCV Rack is built for musicians, not software developers, many who do not know how to unzip a downloaded plugin. This is perfectly fine, because musicians can do many things that I can't. So to make it possible to use for the masses, an account system is best, where it takes two buttons to add and install a plugin. The minority who don't like giving their email address in exchange for this generously-made software can still look at the manifest JSON files to get the binary download link, or compile it themselves.