preperation for developmemt

Hi,
I work as an electrical engineer in a new start-up company which is developing a metal detector.
In the meantime the company is of 3 people and we have succeeded in building up a prototype
of the product.

I have received my degree not long ago and this is my first job in the field of electronics engineering.
The next stage in my job will soon be to develop the product itself and I'm not sure which subjects should I prepare and focus on towards the challenge.

I have some help from a physics professor and we intend recruiting another engineer so I won't be the only engineer, but what are the stages in developing a product which concern me and I should read in advance?

I know I'm asking a general question but I can't be more specific about the product right now.
My intention was to refresh the relevant courses which I have learned in my studies and
trying to understand better optimization processes, board design, elector-magnetic fields
and searching for appropriate softwares for electronics modules and maybe magnetic simulations
and searching for appropriate IC.

Thanks,
Amitai