I'm into my 4th year now mate and tiling is very rewarding but also tough when starting out.
Be prepared to work long hours for not a lot of money at first. You have to price by M2 on most jobs and current rates are quite low so if your not fast you won't make loads. DON'T let that make you compromise on quality, it takes years to build your reputation and one job can ruin it!
The best marketing you can have is a website IMO, I don't do any other but that now! Get a decent one that looks the business, it showcases your work and its the first thing a customer sees if that's how they found you.
Get your card out everywhere,
tile shops, kitchen showrooms, bathroom showrooms, conservatory showrooms, basically anywhere that might need a tiler, go into these places and sell yourself. I did this loads and eventually got in with a kitchen company, I now do all their tiling and the joiners, plumbers, and electricians! If it wasn't for that I don't think I would have got this far!
I now do really well through word of mouth because I've built my reputation but I'd say it's taken a good three years to build it.
You'll learn loads from this website, a good tip is just to read other tilers questions and try and answer it in your head, then read all the replies and see if your right, if not, you've learnt something! That's what I did at first, still learning all the time!
Hope that helps a bit, good luck, and if you ever want to know more give me a ring and I'll answer any questions you want. I know it's tough to start out on your own but if your really determined you'll do well.