When buying produce for juicing, go organic. Variance in quantities is listed as it depends on the size of, for example, beets, which can be small or huge. Scrub or soak produce prior to juicing, but do not peel.
Chop produce into the appropriate size for your juicer, then juice according to the manufacturers directions. Strain if desired.
Notes
If your beets come with the beet greens attached, you can juice those as well, but the color may be a bit muddied because green and red mixed together make brown. Still full of nutrition.