Personally, I stay clear of any mown grass in summer, move out to the edges and into the undergrowth. If you can, practice at the beach first (tidal estuaries are usually virgin ground - A lot of what is mud today was sand not that long ago…)
Ask family and friends if you can have a look on their properties first, get the hang of pinpointing where a target is, and how deep. I have moved into pretty much just doing permissions when not on the beach. So much easier without having to deal with know-it-alls - Who are usually breaching several dog bylaws (fouling/leads/kiwi zones etc) when they challenge you anyway.
Some old-school types frown on pinpointers as ‘cheating’ but after 30 years detecting I love the ability to surgically extract shallow finds with no disturbance at all, and they save valuable time when in the sand. So would put one of these high on your list.
And practice! aim for a minimum of 20Hrs slow, methodical learning.