I have a small Houston-based computer shop where I offer all kind of accessories, including gaming system, PCs and laptops for homes and offices, and more. Despite all of the material, the sale is not satisfying. So here I'm looking for suggestions regarding growing my sales. Kindly share some ideas that can help me improve my overall business

you could use a social media e.g. Facebook to advertise your shop. you could also buy advertisement on a radio or on a social media to advertise to thousands 

I have an idea for your business, Since everything is digital now, I'd recommend you to make a website for your business. This way you could reach more people from different cities or even from different countries which will be a great benefit for your business.  I'd even suggest you hire some of the top agencies like  logochemist, designrush, dexigner & Brands Design for your business website. They are one of the best in the industry!