First you must pick your exchange. Stock markets vary massively around the world but can be categorised according to two attributes: geographic focus and customer size.
Geographic focus: Some markets are principally (or exclusively) focused on trading the stocks and shares of local companies while others concentrate on the equities of international businesses. For example, Mumbai’s Exchange caters mainly for Indian companies while New York’s Nasdaq trades global equities.
Customer size: Some markets are targeted at only very large companies while others deliberately set out to attract smaller, younger listings. In the UK, the London Stock Exchange’s Main Market is appropriate for larger companies with relatively stable risk profiles while AIM styles itself is “one of the world’s leading growth markets” attractive to smaller, younger, riskier companies with high potential. London’s Plus market competes with AIM for the best European small/mid cap companies with a high potential.
Having chosen your market you must choose your advisors. You will need an Accountancy firm, a Lawyer, a Broker and an Investor Relations/PR firm.
Armed with that expertise you will set about creating your Prospectus (the document that tells potential investors all about you) and a presentation that sells your company to those potential investors.
The accountant will makes sure your numbers are accurate, the lawyer will ensure that everything you say is true and the broker will get you in front of as many investors as they can.
All of this can take anything from 4 months to achieve through to infinity. Sadly, although many succeed, the process is by no means guaranteed and many IPOs (initial public offerings or floats) are abandoned (or “pulled”).
If it does succeed and you accumulate enough people wanting to invest in you, at a price acceptable to the existing shareholders, then your shares are admitted to the exchange for trading. And your life as a public company begins, with cash in the bank and a new public profile to maintain.