New Ecommerce entrepreneur in the making, couple of questions though...

I've been doing some research on starting a Shopify ecommerce website, using dropshipping primarily from AliExpress.

I actually set everything up according to some information I obtained from Fred Lam (minus his expensive automation software). Then I decided I hated the niche I chose and I think I'm going to start over. I never actually purchased any Facebook ads so I didn't really sink any money into the enterprise apart from purchasing the domain name.

I do have some questions and hopefully I can start off on the right foot this time and prepare myself for success.

1. Niche selection

I know this is a broad topic and there are a lot of different opinions out there. I don't know whether I'll be able to choose the perfect niche this time, but I want to get to the point where I'm making SOME sales, then I can tweak the formula for better success.

I've heard some people recommend that you create a domain name and store that could serve several niches so you have more flexibility to morph your strategy over time. I'm not sure whether this is good advice or not.

2. How many products should I have listed to start?

I'm thinking I maybe should have fifty products listed for sale, covering maybe five categories. Then run some testing using Facebook ads, then add more of the type of products that are selling and get rid of the ones that aren't.

I'm looking for some general tips on how many categories within my niche I should have, how many products I should have in my store in total and how I should expand or contract my inventory over time.

3. What should the price range be for my products?

The other dilemma I'm having is figuring out what the proper ratio should be between expensive items and cheaper items?

I'm guessing that the general categories would be: $0-$20, $20-$50, $50-$100, $100-$500, and $500+

There also might be a category of free plus shipping that some people swear by.

I'm wondering if there is a percentage breakdown of how much of your inventory should be assigned to each price point?

I guess these are my initial questions. Ideally, I'd like to be able to earn enough money to quit my day job and set my own hours. Hopefully I can do even better than that. I've been sitting on the sidelines for too long, but I've been constantly reading and absorbing information on how this all works and I'm ready to take action.

Thanks for any help you could offer.