Research selling prices of items similar to yours. Look up completed sales or current listings of items similar to yours. Find the high- and low-end prices, and price your object around the median price level. If you want your item to sell quickly, price it at the low end. The condition of the item also affects the price. Items in poorer condition should be priced at the lower end. Also, consider how many listings there already are of items similar to yours. If many similar items will be competing with yours, you may have to set the price lower to get the sale.
A great point you made there though. Too many people try to take on too much at once and end up spreading themselves too thin – trying to conquer all the niches at the same time. Marketers also do this with advertising. Instead of sticking with one platform until they are generating a consistent number of leads they will jump from platform to platform, in essence chucking a load of crap at a wall and seeing what sticks.
How much will you make? I think my best month with Google AdSense was almost $5,000 over the last ten years. That amazing month blew my mind since it was actually near the beginning of my blogging journey. When you go from making zero to $5,000 in a month, that will rock your world. For me, it also got me even more excited because I knew there were other ways to monetize.
If you have your own eCommerce store, social media is the perfect platform to showcase your products. Demonstrate your products in use and tell your social following why they need to buy your merchandise. Most social media channels allow you to add ‘buy’ buttons your pages, allowing your followers to easily click through to your site and make a purchase.
Find a profitable niche. Starting with your interests, write down as many niche ideas as you can. Think about topics people might search online. Ideas include passions (like surfing or body building), fears (like spiders or speaking in front of crowds) and problems (like getting out of debt). Do keyword research to see it others are interested in the topic. Find out if a domain name is available that matches the keyword 100 percent. 
Running a coupons website can be very lucrative. Find a coupon niche, select a WordPress coupon theme, and then display relevant coupons on your site. When your audience uses the coupon codes or discount links, you will earn an affiliate cut for example you could set-up a site dedicated to iHerb Coupons or add a page to your website with Web Hosting Promo Codes. Coupon websites are quite high maintenance as they need to be constantly updated with new offers. However, if you build up an engaged audience and allow them to post coupons and discounts they have found themselves, then quite quickly your workload will reduce.