You can make your free-hand lines smoother by doing a bigger picture. The shaking from your hands will become less visible when sizing down the final image to the size you want it to be - you won’t even see the signature afterwards.

I would also suggest reading this tutorial on DeviantArt for better outlines if you’re working with Adobe Photoshop. The pencil tool is the way to do outlines of love without needing a tablet.

Keep just one thing in mind, Fawriel. All these things are easier said than done. One simply doesn’t jump to being professional from one drawing to another. I think your drawing is well done. Sometimes the lack of “that’s nicely done” comments on critique can discourage you from posting more art but don’t let it. Radium gives awesome advice here (<3 You Rad!!) that’s in my personal opinion worth to note down and keep in mind. (Although he could be a little more specific sometimes but oh well… ;-P)