hi! i am a doodle blogger as well, and i also use paint tool sai! i find that my lines are more blurry but i don't know how to fix that. could you tell me how? your lines are quite solid. thankyou! <3.
If you’re a mouse doodler like me, i always expect that my lines would be like squiggly and wobbly-like but here’s the trick. :P
First, the Mouse should be kinda heavy so that you can control enough its movement. its a good thing if your mouse has batteries (surely its heavy) and if not try to find something you can put on to make it heavy or have a mouse pad with you. I prefer to use laser mouse than the rolling ones or whatever that may called.
Second, Since you are using Sai. Try to adjust your stabilizer located at the upper right corner of the screen. The higher the better, it will help you alot to achieve those smooth lines. Another thing is you can use a line layer rather than the ordinary layer, its located just beside the ordinary layer.
Just like you, I also experienced that problem but always remember that Practice makes perfect. You may see that as time passes by, your lines are improving well. And after a month/s try to compare your first drawing and your latest drawing, you’ll see the improvement.
Before i forgot, always save your doodle as .png i prefer it than the .jpg file - i find it clearer than the .jpg
i hope this will help you alot. have a nice day and happy doodling!