Glass Palette
Who doesn't have left over glass from an old frame? I love using glass as a palette...keeping in mind you do have to be careful around the edges, (taping, sanding them or otherwise protecting yourself from the sharp edges.) You can even buy an official glass palette from your art store, but to save a few dollars, I'll just grab what I have around the house. By far, I find glass to be the best surface to mix my paints on. It cleans up soooo easily, and if you've left paint to dry, no matter, a razor will get all that dried on paint off. I never use the disposable palettes that seem to be so popular. Yes, you just throw them out and don't have to clean them, but I find the paper's surface characteristics less than desirable. For one thing, the paper tends to buckle as I mix. If I go to class and I need something portable, I'll bring a 11 x 14 or even smaller glass to work from. Again, you have to be mindful of sharp edges, but I encourage you to at least once try it. It's also a good idea to put a gray cardboard underneath the glass to provide a neutral tone to mix upon.
Chipper Brushes
Chipper brushes can be picked up at your local hardware or craft store and they are dirt cheap. I love these brushes! They're good for blending and softening edges - and clean up incredibly easily.
Murphy Oil Soap
I used to really struggle with cleaning my brushes well. Once I discovered that Murphy Oil Soap for brush cleaning, I never looked back. Once in a great while I'll forget to clean an expensive brush until the next morning and find paint is really coated on it. No worries, Murphy to the rescue - usually a good soak will remedy the situation. Also, if you get paint on your clothes, pull out the Murphy's again...
Viva Paper Towels
Don't even think about starting a painting without your Viva close at hand. I could and would happily do a commercial for these paper towels. They are incredibly soft, and I can't believe I ever used anything else. I buy them in bulk and ALWAYS have them on hand.
Hand Mirror
It never ceases to amaze me how my mistakes and drafting errors stand out when viewing my work in reverse in a mirror. Try it, I guarantee it. Have your mirror always within easy reach and reach for it often.
Brush Washer Pot
I don't know how in the world I ever painted without my brush washer pot. I often struggled with "muddy" colors since I wasn't keeping my brushes clean during my painting sessions. This wonderful little invention (which has been around forever) makes the process of keeping brushes clean a snap...
IPad
Of course it's always best to work from life, but sometimes you're forced to work from a photo. What a difference it is to view your photo reference from your IPad! Subtle color changes are clear, you can zoom in...I admit even if I'm working from life I'll snap a picture of my subject and view it from my IPad so I can enlarge details and see my subject from a different perspective. Of course you can work from a regular size monitor as well...but if you have space constraints, or if you want to be able to bring your image to class, the IPad is a great alternative.