I'm going to set up my online business soon, I'm just honing my skills in javascript, XHTML, CSS, PHP.

I'm going to register a domain and rent a server soon, just finishing my book on SEO. I'm not sure how this is going to turn out, I will set up this website, make sure it is at the top of google, I will start getting business cards etc. Then when it comes to actually doing the jobs people would like me to do, I'm worried that I might get stuck, what if there is a job that I just can't figure out how to do, I've been watching videos of coding online but I'm wondering how that will work out in real life environments, applying the code to the website, what if they don't like what I've created for them and give me a bad reputation?

Building my website is going to give me a bit of practice on what to do, I will be more confident in creating websites when I do this.

I'm reading these books to get my confidence up, so that when I am actually creating websites for people I am sure what to do and that I don't get stuck. If they know that I am new will they expect me to screw up? What if I do screw up? How am I going to say that to them? "Uhh sorry, I can't figure out how to do this.", what if they give me a job that is too hard, what will I do?

And lastly is there anything else I need to consider? Anything to do with tax and registering a business, I surely can't just make money on the quiet without paying tax or anything like that. Is there anything that I should be careful of when setting up the business? I don't want to miss something out when setting up the business. I'm considering creating the website on wordpress so it can easily be updated, apparently it's good for SEO.