HOW CAN I SELL NICHE PRODUCTS IN HIGH DEMAND TO TARGETED CUSTOMERS ???

So, If I'm understanding you properly

You want somebody here to guide you/hold your hand step-by-step to a profitable business...am I right?

You can sell your product's through social media marketing by using targetting customer according to your product category and you can boost your sell.

So do you want to sell to busines or do you want to sell to customers?? I think the approach would be very different. In the original post you said cosmetics stores in London or Stockholm ... are you anywhere near these places? Or why these two?
The most promising approach I'd guess is contacting local stores in your area, set up a meeting and present your product. Leave samples. Have all your data at your fingertips during the presentation: Why they should stock your products, what's so great about them, how they can improve their own sales / ROI / customer relationship with your products, how they can get an edge over their competition selling your products, ... basically everything that's in for THEM when they decide to stock your stuff.
Getting your foot in the door with one local store could open doors to customer reviews, likes and shares of your products on social, etc.
Another thing you could try is some sort of press release about your stuff. Stores looking for good new products to stock may have an alert set up to get notified. Just as an idea. I have no insight at all into this kind of business.
Other than that, B2B networking is best done on linkedin.

If I'm understanding you correctly, you want to sell cosmetics to beauty stores/retailers. If that's the case, than I think you've drastically underestimated how hard it is to do what you're asking.

You said you have no sales history and no platform. But, expect a retailer to hand over money to stock your products? In any retail store, shelf space is limited. A retailer would be crazy to buy from an unknown source. And, even if they did, they wouldn't do it on terms where they pay you $x.xx for x amount of stock. The retailer would certainly cover themselves with a buy-back clause should they be unable to sell your product(s). Most retailers order products through distributors, which simplifies rhe process. But, it also reduces the profit margins for everyone involved.

If I understood you correctly, I think you need to do more research on getting products into retail stores. Then decide if that's something you're able to do with your product(s).

I don't know about the EU ...

but in the U.S. anyone can walk into a good public library and find reference books listing U.S. companies by type and the kind of products they sell (SIC code). All the company details are given so you can contact them directly. It's not that difficult at all to find all the contacts you need.

This will give you an idea of what I'm referring to:

Standard Industrial Classification

Steve

You can sell it through social media's, since people are very active on this platform.

Well, as all say above, you can contact the near retail stores that'll definitely beneficial for you. There are many people who sell their products through retail stores. Apart from these you can create a page of your business on various social media platforms and connect them with each other. For example, you create a page on Facebook, Twitter, and Instagram. Whenever you post on Instagram or any other platform just click a share button and it'll also display on other social media accounts. Due to this, you'll get more followers and customers as well.

Find people who already have lists of buyers in those geographic areas and target niches. Partner up with them.

Just curious Kubson: would a very basic online shop where you sell through chat and get paid through Paypal make it for you?