As I mentioned in my videos, these brushes are for painting the final thin, transparent layers. This method is used to show natural translucency of the flower petals. Dilute your oil colors with oil painting mediums (artist grade linseed and walnut oils are some of them) to reach necessary transparency and consistency. Give yourself plenty of time to practice working with the brushes. You can use something washable, like a piece of glass or a plastic sheet, placed on top of paper, before painting on canvas. You will need to get used to working with large brushes to develop the skills painting flower petals and leaves. You can perform exercises in black and white first, or choose a different not bright color, such as raw or burnt umber, in order not to get distracted by color search. Once you figure out the brush stroke and build up muscle memory, add color to your practices on temporary surfaces. Move on to canvas when you feel more confident.