It looks like you are off to a good start, you are finding targets in all categories, (iron, foil, tabs, nickel, penny, dime, quarter). And you have downloaded the manual which is good. There are a lot of ways to set up the F70, a lot will depend on what you want to find, coin, jewelry, relics? If you go back a few years in the F forum, there was a fellow named REVIER. He was a F70 guru, experimented with a lot of different settings and then shared the results with the forum members, lots of good information. Sadly, he passed away a couple years ago, but you should be able to view his posts from a few years back. There is a lot of them and good information.
I have used the F70 for several years, I ground balance, usually run the discrimination low ( 0-6 ) sensitivity around 50-60, thresh around 0. Those are the settings that I usually use, don’t be afraid to experiment with different settings, try to find what works for you. Some people make a mistake and run the F70 at max sensitivity which could produce excessive chattering. Good luck, I think you will like the F70. Good battery life, not too heavy, different size coils to choose from.