I mean, if you’re looking to hire someone to help build out a Shopify store, that is a service that I offer! 
Before hiring anyone though, you should have a good idea of what you’re looking to sell. Don’t just ‘make a store’ to ‘have a store’. You need to have a game-plan in mind, before hiring someone, otherwise you’ll end up with something you’re not passionate about, and that’s the quickest way to lose motivation in the ecommerce world.
Anyone who claims to be able to build you an ‘overnight success’ of a store isn’t being honest. If that’s what you’re looking for, then you should think about purchasing an established business and just take over something that’s already working. Beyond having high-quality products, at a reasonable price, with a decent-looking website – you’ll need to put in a lot of work (and potentially money) into marketing to have a successful online store. Simply building a beautiful website isn’t going to generate you sales, if you don’t have a plan for how to get ‘the word out’ about your new store.
A lot of people use Google Keyword Trends (https://trends.google.com/trends/) to try and find things that are ‘on the rise’ in terms of popularity (based on what people have been searching for on Google).
As far as running ads go – I always recommend to my clients that you have someone in-house who learns how to do them. They’ll probably not be successful (or profitable) right out the gate, but it’s better to burn money learning how to do them yourself, than hiring an ad agency to do the same thing at a premium. Instead, if you want to spend some extra money right away, then hire some graphic designers or video editors/creators, to create the content that you use for the ads. That’ll be better bang-for-your-buck.
Once you find an ad campaign that’s successful, that’s when you should think about reaching out to an ad agency, so that they can help optimize things. This is just my 2-cents worth though – there are definitely folks who disagree with me, and decide to hire an ad agency right from the start. If you can afford it, then sure – but if you’re trying to make every dollar count, then it’s best to do the ‘experimenting’ yourself, so that you’re not paying a premium for it.
When you go to hire someone to help build the site, it also helps if you have a few stores/websites that you can link the person to, that you really like, so that they can get a better idea of how you want things to look/work. I wouldn’t recommend paying for any ‘site mockups’ (a lot of folks do ‘figma’ designs, and then try to hire people to match the designs/mockups). It’s better to hire an Expert who has a portfolio of sites you find nice/professional-looking, and have them work with a theme from the Shopify theme store that’s as close to what you want, so that you can avoid spending a small fortune on custom-coding edits. Working with what’s available is 10x easier for whichever Expert/Partner that you hire, than trying to match something super-custom, from a graphic artist who didn’t even have Shopify in mind when they made the designs.
TLDR:
- Figure out what you want to sell.
- Source the products before you even start building the site (ie. know where you’re going to get your products from).
- Plan out your content (logo, banners, text for your various pages, product pricing, etc.).
- Hire an official Shopify Expert/Partner to build the site, using a theme from the Shopify theme store.
- Pay a graphic designer or video editor to create some nice content to use for your ads.
- Learn and run the first few sets of ads yourself.
- Once you find ad campaigns that works, think about hiring an ad agency to take you to the next level.
Good luck! 