Not OP, but I am a dedicated amateur of several years and a less than complete absence of skill [1] [2] [3]. Asked the same question, I'd answer like this:

- Unless there's a really strong reason I'm not aware of, don't bother with DNG conversion. If Camera Raw can convert your raws to DNGs, Lightroom should be able to work with your raws directly, eliminating a step.

- I use presets heavily when working with multiple images of the same subject, or from the same shoot. As long as exposure parameters don't vary wildly from shot to shot, this lets me perform most edits just once, on the first shot I edit, and then apply them to several others. From there, minor tweaks usually get me to done. (In most cases, I just crop, adjust per-channel hue/sat/lum, and tweak any edits from the preset that need fine-tuning for the image I'm working on.)

- This one might be a little controversial, but it's been by far the largest single improvement to my development workflow: Get a Loupedeck+ or some other closely similar editing console - specifically, something that's designed to work OOTB with Lightroom, and not something that needs a lot of assembly and customization to be usable.

Yes, a Loupedeck+ or similar will restrict your choice of software to that supported by the device manufacturer, and Lightroom's always going to be the best supported because it is universally the standard. And, yes, a Loupedeck+ costs $250, and the market goes up from there. It's still worth every penny.

The programs we're talking about here are complex, and they have complex UIs. Operating those UIs by means of keyboard shortcuts and mouse pointer sucks rocks. I know because I tried it, and I learned to do it, and the whole while I hated it and hated Lightroom and hated developing my raws because of how slow and picky and painful a process it was. Even with presets, I could at best manage a few photos an hour, and each hour was more frustrating than the last, to the point where the foreknowledge of the editing burden began genuinely impairing my desire to take pictures at all.

Getting a Loupedeck+ made such a difference that trying to describe it tempts me to cliché. Since this is HN, I suppose I'd put it thus: It was like going from using Notepad++ to using Emacs - except that where Emacs required a year's learning curve to achieve the kind of proficiency that made the effort worthwhile, getting proficient with the Loupedeck took less than a day.

I found it astonishing how much better the whole experience was when I had all of the develop-mode controls literally at my fingertips. Instead of endless fiddling about with a mouse pointer to select, hold, and precisely adjust a tiny slider, now I just turn a knob until the value is where I want it. For everything. The worst it gets is that, for some less commonly used controls, you have to hold down a button while you turn the knob. But it's a physical button on the actual device and, as with all the others, your fingers quickly learn where it is - which is a less obvious but very real benefit in its own right: with a physical editing controller, muscle memory comes into play.

Reading back over what I've just written, I suppose I sound a bit of a zealot on this subject, but I don't actually mind. It's a fair representation of how I feel. I genuinely cannot overstate the extent to which I've found having a physical edit controller to improve my experience of editing raws in Lightroom.

Obviously I favor the Loupedeck+, but it doesn't have to be that one - although I have to say, $250 is pretty cheap compared to literally anything else in the photography space, and in terms of value per dollar I legitimately do consider it right up there with the D850 body I use for macro work. The point is, get something, and get something that works out of the box. You won't regret it.

(Side note: You can customize a Loupedeck+ through its driver software, although I've never felt the need to modify the defaults. Also, I'm not a paid reviewer, nor have I received any consideration from Loupedeck; I'm just an extremely satisfied customer who uses it to develop everything, including the images in the pages linked below.)

(edit: I didn't notice you mentioned Lightroom 6, which may explain the need for DNG conversion. In my opinion, $10 a month is worth getting a Lightroom with current camera support; I don't love the subscription model any more than anyone else, but I'm willing to tolerate it. That said, as far as I know, the Loupedeck+ driver software does support Lightroom 6, so everything on that subject above should remain valid for your use case.)

[1] https://aaron-m.com/2019/07/08/polistes-metricus

[2] https://aaron-m.com/2020/08/09/vespula-maculifrons-priocnemi...

[3] https://aaron-m.com/2021/01/23/auplopus-architectus-metallic...