I don't think that one platform of SM is better than any other, think it's just a case of trying them and seeing which one works for you
We've found that FB brings in personal clients and Twitter brings in business clients but for us, Insta is full of CFers who want something for nothing, it may be entirely different for you though, just try them and see what happens.
If you haven't got a website, Iset up a FB business page first. It's free and looks more professional than using your own profile.
Once you've done that, you can start adding posts and invite all of your friends and family to like and share your page.
You can also find groups on FB that might contain potential customers. Some groups allow advertisers. One of our local FB groups allows you to advertise your business with no charge but only on a Tuesday. It's just a case of finding which Groups work for you.
Square Space website maker is very easy to use and I really don't think that you'd have to pay someone to build it for you. Just set aside some time to work on it so it's exactly how you want it.
The added bonus of doing it yourself is that you can edit it as many times as you like without having to keep paying someone else to do alterations for you.
If you do want to put some money into your advertising, rather than paying someone to do your website it might be worth paying a decent local photographer to do some stock photos for you to use in advertising, both on your SM and on your website 