For me, art and story in VN is pretty much 50/50. I've been playing a lot of mobile VNs lately, and while they do have good art, the stories/dialog are boring so I haven't been to interested in playing them much. I'd play game with your art in it as long as the characters and plot were interesting.
If you're having problems getting used to your tablet, try taping a sheet of paper over it. As for your linework, you could always try scanning in your artwork and then trace it or tape it to your tablet and trace over it. Also, try not to move slowly while doing the line art, faster strokes tend to make the lines less wobbly.
You could also try using
FireAlpaca, which is a free drawing program that's similar to Sai, but completely free. If you're using Photoshop, you could try out
Lazy Nezumi to smooth out your lines. It used to be free, but now there's a pro version with a free 30 day trial.
In regard to poses, I recommend looking up reference or trying out the pose yourself. If it feels awkward for you to do, it'll probably be awkward to look at as well. XD
Good luck!