I had mixed feelings about oil pastels, a love-hate relationship, and now I love them! The key is, to learn the medium and get GOOD quality pastels. Of the European brands, only Sennelier and Caran d'Ache Neopastel are worth buying. On a tighter budget, Mungyo from Korea are great (Amazon, Ebay) but no open stock.
You can also modify cheaper, tougher oil pastels (e.g. Jaxon) with baby oil to become soft and buttery. "Penaten" brand is made of high quality parafine oils and surely available in Hungary. Instructions a bit further back in my blog. Added benefit: you can mix and make any color oil pastel sticks you like!
Oil pastels play well with (over) other media including watercolor. I underpaint with gouache - works great. It may also be worth investigating the water repellent quality, kinda like masking.
They work on pretty much any substrate or paper. A matte watercolor paper works fine, also a mixed media paper.
Blend with fingers, Q-Tips, tissue, tortillon (estompe), silicon color shapers, or paint thinner on brush. It depends on both pastel and paper brands which blending method works best.
Try it!
Thanks so much!