Firstly, the usual suspects: "youtube tutorials", "references!", "draw every day!" "learn basic anatomy!". Do those.
Along with that:
If you want to get better then you've got to push yourself. Do it incrementally, don't trying going from Kirby doodles to photo realistic portraits of our lord and savior Donald Trump, but push yourself and don't be afraid to fail. You're going to fail, a lot, but "success is built on a foundation of failure"
(if that's not an existing quote, I call dibs). If you just stick to what you're good at then your Kirby's might end up looking majestic as hell, but your backflipping Metaknights aren't gonna be too hot if you avoid doing anything more complicated than Kirby...Aim for those majestic backflipping Metaknights.
Learn how and when to be critical of yourself. It's important that you can look at something you've done and say "this bit here looks like ****, I totally ****ed that up", but it's also important that you can look at something and say "that looks better than the last one! I'm gonna do another!".
It'll keep you motivated when you can see where you've improved rather than just where you've failed, it'll also stop you being the mopey artist who's always sad and has no motivation even though they've come a long way...Nobody likes that guy...So many people focus on their failure rather than their success, don't do that.
Grouping the last two points into one metaphorical example: Don't be 'that guy' who always draws characters with their hands behind their back because they tried hands once but they looked like deformed sausages, so they just wrote it off as something they simply can't do. Draw those god damn hands, even if they look like weird manky spiders, and congratulate yourself when they finally resemble a hand in some way.
Another thing: actually 'learn how to do things'. I'm not just reiterating the above there, I mean actually learn how a certain thing is fundamentally done. Go onto any video tutorial on Youtube and read the comments, I guarantee you will easily find a comment asking to do:
- something the 'channel' has already covered in another video but on a very specific character instead
- something the 'channel' has literally just covered in the exact same video but on a very specific character instead
- essentially a step by step tutorial on their favorite anime character doing a specific thing totally unrelated to anything talked about, suspiciously written almost like they didn't even watch the video
I watch Mark Crilley's videos, I just like watching the guy draw, it's comforting, but his video's comments are full of that. He had a video about how to draw hats and there was at least one comment complaining that he didn't show how to draw a specific type of hat, with others asking to draw their favorite 'hatted characters'...Even though he kind of actually did in the video, he gave all the 'tools' required to be able to draw that hat.
Morale of the story: Learn how to apply what you learn to other areas. It'll help way more in the long run if you can do that rather than relying on online tutorials for literally every little aspect of what you draw...Yano, instead of asking for a step by step guide on how to draw a rectangle when you already know how to draw a square.
Also, reinforcing what Luxanna said:
It's what I do. I've been drawing the same
(slowly expanding) handful of characters almost exclusively for like 2, 3 years...Comparing a doodle of the exact same character from back then to now is like night and day though, and I've learned how to do so many things by taking what I learned with those characters I'm comfortable with and applying it elsewhere.
For myself, learning how to do 'new thing' is a lot easier and I'm a lot more comfortable when I'm doing that 'new thing' with a character etc I'm comfortable with, something new on something that I know I can already do. Once you can do it with that character,
(as I said above) you can then apply that elsewhere. It's somewhat like staying in a comfort zone, but also still pushing yourself.
I suggest you carry around a sketch book
So many people suggest it, so few actually follow through with it. Mine is always in my bag
I take my bag basically everywhere and a lot of things I've 'gotten the hang of' or just improved on just because I was sat around bored with the opportunity to draw, so I did.
Sat at home and there's a crap movie on? Grab the sketch book. Sat in work with a hand free? Draw whilst I'm saying "I understand" to an angry customer over the phone. Go to the pub and everybody is being 'social' on their phones? Pull out the sketch book and draw
them all getting hit by a car a cat.
It's not a necessity, but limiting when/where you can draw by the materials you need only being available in one or two places can be a real pain if you're just in a place where you can or you just suddenly get the urge to do so.