The biggest thing here is practice, practice, practice. You can do it!
If need specific instructions on how to mitre:
• How to Mitre Tile for Beginners: A Co...
Tenax epoxy and pigment kit:
https://amzn.to/3VjC0ve
Epoxy I use here:
https://amzn.to/3VhdOt5
Sanding pads:
https://amzn.to/3IVZ7Vj
**the links above are amazon affiliate links. If you purchase through them, I will receive a small commission at no additional cost to you :)