Not sure if anyone's still having trouble, but I recommend sticking with it like others have said.
The first time I played around in it, it was really confusing and unlike any other program I've ever used for art. After a few hours though, I got the hang of it and figured it out. Here's some tips I have if you're still having trouble:
*If you're using the online editor (linked above), any images you import to trace off of will appear noticeably darker depending on the background you're using. For best results, I recommend putting down 2 large white squares over the SA area as your first shapes so that your image will display the proper brightness and colors.
*Utilize groups in external editors to move multiple layers at a time. In the online editor, this is done by right-clicking the layers panel and selecting "Add Group Inside". To begin working within the new group, right-click it and select "Add Symbol Inside". This is especially helpful if you're working on multiple subjects (characters, objects, etc.) or adding text.
*Another important tip is to double-check what you have selected before you try to move anything. If you change the transparency on your imported image (if you're tracing) and then go to move a shape without selecting it in the layers panel first, you will move your image instead. There is no undo button for this, meaning you will have to reposition your image. I do this multiple times per SA so it's not the end of the world, but try to keep it in mind.
*After creating your symbol art in any external program, it will most likely look very different once you import it into the game. I recommend saving the finalized art you've made from the editor as a static image (.PNG, .JPG, etc.) and use it as a reference to make fixes using the in-game editor. This means changing colors, fixing transparency, and in some cases even moving shapes around. I've had some SAs zoom out to reveal very noticeable gaps that had to be filled.
*I also want to point out to limit your expectations. SAs are created on a grid and displayed in small resolution, meaning that you will have to compromise on your work at times and be extra creative, even when you're tracing. Realism is very possible (as I'm sure you've seen in-game) but remember that those extra details might not translate too well from a distance. Simplification is your friend. You get a little over 200 layers to work on them as well which seems like a lot, but you'll start running out faster than you think. Make sure to go back as you edit and change or delete any shapes that aren't necessary to free up space. You don't wanna create the perfect subject and then realize you have 3 layers for a backdrop (speaking from experience). And finally, be patient and SAVE OFTEN.
Beyond that, it's all about playing around until you're comfortable and letting your creativity flow. Your first SAs might be a little wonky or not represent your best work, but as long as you keep at it, you will improve.