Best advice I can offer without you asking anything specific, is to start with your sens and threshold low (it's still go 6"+ deep even with the lowest settings) so the machine is the most stable and you can focus on learning the tones. Iffy signals tend to be junk (rotted zinc pennies for example) or deep targets on the fringe of detection.
Keep the disc low, notch nothing, and dig everything for a while until you learn what the numbers are telling you. Once you start to learn the machine then start testing disc and notching if your area needs it (I run my disc at 6, and notch nothing, I'd rather be the one to decide what to dig vs the machine masking out targets for me).
Once you feel confident that you've learned the tones and have a feel for the TID #'s, disc and notch settings, then start playing with the sens/thresh. The higher they are, the noisier the machine will be, so keep them low to begin with or it'll be overwhelming. The F70 is almost identical in programming and performance to the F75, so reading the F70 AND F75 forum posts will help you glean useful (and some not so useful) tips to weave into your hunting grounds and style. The JE mode (jewelery) mentioned on the F75 is the same as the SL (slow) mode on the F70, EXCEPT according to Nasa Tom if using the JE mode on the F75 it will automatically reprogram the disc levels, but not so on the F70.
I've made some of my best finds with the F70, so it's definitely a capable machine and the more I use it, the more I like it.
Most of all, have fun!
hh,
Brian