No matter your skill level when it comes to art, switching to a digital medium is no easy task. There seems to be a common misconception that digital art is cheating or easier than traditional art methods. While there are features that make creating art easier, (using layers, opacity, unlimited color options, erasing, etc.) it still falls on the artist to put effort into their creation. You aren't having a computer create your piece; you still have to draw it.
1. Use layers
One of the first things you should learn how to do in your art program is how to create new layers, and how to use them. It can be incredibly beneficial to break down your piece into different parts and separate the parts. When you have to make changes to a specific part, it'll be set aside from the rest of your work, making it easier to edit.
2. Invest in a tablet
If you start out using a mouse to draw, you'll start to compare yourself to other artists. There are some things that impossible for you to do with a mouse, such as pen pressure sensitivity. It'll make your journey in learning how to draw digitally a lot smoother if you get a tablet as soon as possible. I personally don't recommend investing in the most expensive tablet right on the get go. It's possible to find cheap starter tablets that are under $100! Just make sure to get one that has positive reviews. Once you're more comfortable with the transition to drawing with a tablet, it won't be as daunting to invest in a more expensive tablet.
3. Try a variety of programs
A lot of people seem to think that photoshop is the only program to draw with. PaintTool Sai is also a popular drawing program, but it isn't free (legally). While having knowledge of photoshop is great for a career, if you're drawing for fun, it's not necessary to drop money on it. There are lots of other art programs available online for cheaper, or for free, that are simplified/more streamlined for artists. Start out using free use programs as you learn, such as GIMP or Fire Alpaca, to avoid sinking more money.
4. Save multiple files
As you get used to drawing, be aware of how you're saving your files. Having an organized naming system and folders is great, although most artists have a hard time keeping up with it. If anything, I recommend making sure you know what types of files you're saving your pieces as. Make sure to save unfinished pieces as a .psd/.sai/.mdp (usually whatever the default is in whatever program you're in) so you can go back and edit. This way, the layer information will be saved, and you can pick up where you left off. If you're unsure if you want to go back to a piece, it doesn't hurt to save multiple versions, either.
5. Don't quit!
When I first started digital art, I had a preconceived expectation that it would make me a better artist. I was discouraged when I realized it was going to take me a while to adjust to drawing with a tablet. Drawing digitally versus traditionally doesn't automatically change your skill. It's simply another method that you can use as an artist. You'll grow as an artist from trying any new medium, but it takes persistent practice! Even if it seems difficult, the more you try, the more you'll learn!
Below, I'll attach a few images showcasing my progress as a digital artist over the years. I didn't catalog my art over the first few years, but the first few images are from 2011, 2012, and 2013. The last image is from the current year, 2017.