Hi Joanne,
I have a Nutribullet and love it! I used to use juicers in the past but the Nutribullet is 10x easier to use and especially to clean than an actual juicer.
My nutrition has improved considerably after getting the Nutribullet in the last year. It allows me to eat things that otherwise I had trouble digesting.
I usually do mixed greens as a base, and then add in fruits like berries, grapes, apples (or whatever is in season), and top it with either nuts or flax or chia seeds and also water. Sometimes I add greek yogurt. It all blends down to a liquid I can drink.
And like Sharon said, start slow and find what works for you. Good luck!
PS - I first got the Magic Bullet (made by the same company as the Nutribullet), but that is a lot less powerful than the Nutribullet. The Nutribullet works way better for veggies. I also have a big Breville juicer that I sometimes use for making larger batches of fruit juice, but that is getting rare now since it is so much more work to clean it than the Nutribullet.