What works for one painter may not work for another. What I recommend is buy the best materials you can afford. Then experiment, find painters whose work you admire and try what they are using. Experiment! Experiment! Experiment! Here is what I use and some recommendations for beginners.
BRUSHES: My current brush of choice is a Utrecht #10 & #12 Brights. You also want to bring a #4 and #6 brushes with you. The brush type has a lot to do with the end result you want so bring what you have.
PANELS: If you are a beginner and not expecting to sell these paintings then 8×10 canvas boards are fine. These are cheap and you can throw them out easily enough. You will get the best experience in my workshop if you cover the canvas with grey gesso.
PALETTE: Grey Matters Disposable Paper Palette. Cheap and easy!
PAINT: My paint of choice is Classic Artist Oils. If you have ever painted in oils it is likely you have every color you will need for this workshop. The below palette are the colors I believe gives beginners the best chance for success. Some manufacturers use different trade names. If you have any trouble finding a specific color please contact me.
COLORS (4 oz. tubes will be fine to start)
Baby Oil or Thinner
Something for your thinner, such as a steel brush bath with lid
A good quality painting knife
Tin Can for your brushes