* Cadmiums are toxic. Instead of using cadmium yellow, I've used azo yellow ever since the beginning. In London I also bought a "primary cadmium yellow imit". Imit means imitation =not real cadmium. If the tube says "cadmium hue" it aint real cadmium either and therefore a good purchasing choice. Be aware of other heavy metals used in oil colors, like cobalt in cobalt blue (I have a cobalt blue imit).
*I don't use thinner. I use something called "Grumme" in Swedish, and also a brush wash I bought online called Zest-it. I saw they had it at the gigantic artist store Atlantis in Brick Lane London too. Zest-it is a natural citrus based brush wash.
*Eco-friendly paper. Unfortunately I have no knowledge of where to find eco-friendly acrylic or oil paper. My acrylic paper is labelled "acid-free" but it doesn't have an eco-label. At least, my postcards are printed on an EU eco-certified paper.