Hi
It is great that you have a business idea. The question you asked is very real to any business especially when it's a startup. You really don't want to put something out there when there is no niche for it or when it is moving slowly. so here is what I would suggest.
a) Do a thorough feasibility study on the product you are offering. Ensure that your suppliers are genuine and offers good quality. You must know your demographics. Who are you targeting?
b) Who are your competitors and what are they offering in terms of price and quality?
c) Can you match that or can you afford to do a loss leading( getting your product out there at a cheaper price but quality & customer service will give you quantum sales faster.
d) Where do you want your presence? Online only or traffic from both online and walk in?
e) What type of funnel of strategy will get you there at the least cost.
f) Network--Network...Network. (Quality goods needs quality marketing)
A lot of time needs to be put into this.
There is a whole lot more but feel free to set up an appointment with me.
Best of luck.