That's a wide open question. Profits?? Do this. Start by making a list of ALL your overhead expenses. That will include rent, electricity, phone, etc. All the bills that have to be paid EVERY MONTH.
Then, try to determine the profit on the average sale. You don't mention what type of electronics, but I have to think that in today's market, margins are really small.
So now, how many of those AVERAGE sales do you have to make TO COVER THE COSTS?? That's before you make money.
That's a start. The rest of the quesitons have to deal with where? how big a store?? all that... but that can come later. Figure your FIXED overheads first. That will tell you a lot!