Alot of people debate about doing something you like vs doing something that might be boring to you personally but sells well / hot selling products.
I guess it depends on your drive, but I started off doing the last one - sells well but boring to me personally. To be honest yeah it does ok but it's not fun for me - so now I'm going towards only things that interest me as it's just not fun if you don't enjoy your subject matter and becomes a real drag to invest time into and time is your most valuable asset. So try find a happy medium - something that sells well and that interests you too to keep you interested when you have some tougher times.
Don't buy into the "you have to have this app and that app" which shopify will continually try to upsell to you. Every article they write and every email they send. You really only need what you need (like oberlo and a few others, and lots are free too) ..and the less apps the faster your site runs also which is crucially important for selling too, just as important as any wiz bang apps).
I would recommend https://www.signifyd.com/ (signifyd app) in shopify though. One of few I would. They protect you from fraud.. and chargebacks also. I've had a few chargebacks and fraud attempts - you'll feel alot better with this app and they've refunded me any chargebacks they approve also. They also only charge around ~17c - $1 per transaction so there's no monthly fee, it's pay only what you use type app which I think are the best kinds.
Personally I wouldn't sell any make-up or fur products (even fake furs) as these items all come from china, it's an incredibly cruel industry to animals over there, which I care alot about. All make ups must be tested on animals by law there and regulations are incredibly poor so it's a shockingly barbaric industry like their fur industry (even fakes are often real) that I would never support. I'd also stay away from lotions / makeups / anything people can put on their skin like creams, or in their body like no vitamins or anything like that - because these things are highly regulated in Western markets and you need the right certifications to import those kinds of goods and could get into all kinds of trouble if something went wrong with a customer (e.g. the suppliers you buy from in china may not have certified these products like FDA - even if it says on their page they have - or have them tested so I just stay away from those. They are also not responsible under law even though you buy from them and they make the products and you never see the product, unfortunately it is us the merchant who is responsible for these products being imported, so yeah stay away from anything like that, especially baby/childrens products too).
You'll need a fair bit of money for marketing. Facebook and Google will happily eat your spending budget if you don't know how to use it properly so definitely learn how to use facebook ad and google adwords marketing tools properly (lots of videos on you tube). I know a great deal about SEO.. years of learning it. And it's an awesome skill to learn (and continually learn as changes alot) - however in hindsight I wish I'd spent more of my time learning marketing more and I'd say concentrate more on learning how to do that well first - although SEO is an important part of any website and good to learn about too.
I could go on But I'm sure you'll figure your own way as you go.. I also tried to learn and learn and learn.. (in it 3 years on now) and I will tell you just go ahead now and do it, and you'll learn as you go from that experience.. and mistakes.. etc.