Hey @MutilatedMoth, welcome to ILGM. Great question! My first grow, I was overwhelmed by how much I didn’t know I didn’t know. Your first grow will be a huge learning experience, even if everything goes perfectly. It won’t.
The best advice I got was to make sure you have everything you anticipate needing (that’s the hard part) before you even soak a seed. That way, you’re not shooting yourself in the foot because you didn’t have the next size up containers to transplant, and your plants are root bound while you wait for bigger ones…or whatever.
The most common mistake new growers make is over watering, and over loving their plants in general. It’s new, exciting, you want to be in there checking on them and doing something with them at every opportunity. Oooh, they look thirsty, I should give them a drink. Guilty. But Cannabis does much better with too little water than it does with too much. It’s best to let your containers dry up quite a bit (but not completely) before watering/feeding again.
Get a good pH meter and solutions to calibrate it regularly. Blue Lab, Apera, and similar ones are popular around here. The same goes for a TDS meter to measure the strength of what you’re feeding, and to see what the plants are eating. Besides lighting, these are probably your two most important pieces of equipment, if you want dy-no-mite (Jimmie Walker from “Good Times” style) vs. just soso bud.
Speaking of lighting, don’t waste money here. Get the best your budget can afford, the first time around, and save yourself some headaches and again, soso bud. The best bang for your buck, light intensity per watt, is going to be LED, specifically quantum boards. Depending on the space you’re lighting, there are plenty of plug and play options, as well as limitless possibilities with some light DIY. @dbrn32 can help you out here.
I’ve only grown in soil, but I have a veggie garden going in coco right now, and I’m leaning toward it for my next cannabis grow. Soil is great, some don’t require any feeding well into veg, some clear to flowering, depending on the type and how long you veg. On the other hand, with coco or promix or any soilless method really, you have total control over what your plants get fed. In soil, you’re sort of stuck with what’s in it, at least to start, unless you build your own soil. @garrigan65 and @Mrcrabs come to mind, for organic soil guys. Problems can be corrected much quicker in hydro vs soil, but they also happen much quicker in hydro. @TDubWilly and @DoobieNoobie grow monsters in hydro, and can answer more questions on that side. My advice would be to start growing in soil, to learn how the plants behave and what to do when they “complain,” so that should you choose to try hydro later, you have an idea what to do if you have problems. Others have jumped right into hydro and make it look easy. It just depends on what works best for you and your circumstances.
My first grow was a White Widow feminized that I abused the hell out of, documented here: Closet/Frigidank™ perpetual grow
I listed, in detail, all my rookie mistakes. I chose White Widow because I read it was easy to grow. However, knowing what I know now, I’d have chosen something more high yielding, to compensate for my rookie mistakes. WW is a pretty small plant, relatively speaking. I want to say I cleared 38 grams dry, but my memory is not my best feature.
MY best piece of advice to you is to read, read, read, and read some more, journals on this forum, guides on the site. YouTube videos are good, too, but sometimes you have to weed through some crap/bs. Learn as much as you can before you even get started, even as you are starting and throughout. The more you know… Don’t be afraid to fire away with any questions you run into. Someone will be happy to help. You’re in great hands, you’ve found the best bunch of growers on the internet!