I used Faber Castell Polychromos colored pencils. I find the laying down of color and blending very soothing, and love to see the image coming alive with color as I work.
Hope you will give adult coloring books (or calendars) a try. I happen to know that Santa got mine at Bed, Bath, and Beyond (with a $5 off coupon, of course).
Happy coloring....and have a wonderful weekend.