In the US, certs definitely are needed from a business point of view to at least get a potential client to come to you....even if most certs are a joke, those potential clients only know they want a "certified" trainer (if they only knew how easy most certs are to get, they would change their mind). I've met plenty of people with lots of initials on their business card, but yet did not display a good understanding of training....most clients will figure that out after a while.
Your client's results will sell you more than you can ever sell yourself in a potential trainee's eyes. Networking through current clients is definitely a smart way to go, that's when the reputation starts growing, word of mouth spreads and people come to you.
Get your niche, be the "functional training" guy....something people around you are not. Also look in your country as to what the mass public learns about fitness and take advantage of it. If Kettlebells are coming in view to the public, be the first to offer it in your training...or have a special sports performance package for training...stand out and you will do great in your field.
But still....even a basic CPT at least answers that question posed by your potential client of "why aren't you certified".....so have a good answer to that one or people may not give you a chance even if you are an excellent trainer.