I have had my own business for 2 years now, social media has been a big one for me, posting deals in local selling pages helps too, i started mobile, then from home and now I have a shop and staff, started with £30 in my pocket! X
It's hard graft.
You'll have to notify the HMRC, change you car insurance to business IF you're going mobile , liability insurance , keep EVERY receipt business related, even work clothing, petrol (but only if mobile, can't claim petrol for a static location) stock - the lot
Get an accounts book, they're only a few quid, write all your incomings and outgoings
Flyers and business cards at the ready and go door posting