Snoopy- Seeking improvement

I embroidered this snoopy for a mini 3-inch embroidery hoop. It’s to use as a Christmas ornament. This is my second project. The first (I posted here) was a baby blanket with the baby’s name embroidered.

I’m new to embroidery and self-teaching. Overall, I’m quite pleased with this- I think it looks cute. I do have a few questions for improvement though.

I struggle with knowing when to use what stitch. For example, the outline in this snoopy is a weird back and forth between split stitch and back stitch. I felt like sometimes split stitch was awkward (especially around tight curves) and i would just switch to backstitch. Idk why I chose those, if they were the right choices, or if it’s normal to switch between stitches in that way.

For the parts that are filled in, I attempted satin stitch. You can see there are some white spaces between the border and the red center- any suggestions to avoid that? Or do I just need practice?

(Sorry for the crappy pics- my phone camera is not working as it should)

TIA for any suggestions or resources!! :)