Here's a seemingly odd question; How do you know if your business is going to fail or succeed? This is a really tricky one!
Firstly, the statistics for the failure rate of start-up businesses makes (perhaps) worrying reading. Depending upon which information source you look at, circa 50% of start-ups will fail within 4 years.
Most of that 50 percent will have failed within the first two years. However, I don't really think it (the failure rate) is really too bad a statistic if you consider that most endeavours in life also have a significant proportion of non-successes. For example, how many people who try to quit smoking actually manage to do so?
What proportion of people start a fitness regime and then let it slip. I'd guess the percentages are pretty high. So, why would start-up self-employed "businesses" be any different?...No reason at all.
The reason that I have used these other examples is really just to highlight the facts, yes, there are risks (of failure) to self-employment, but then there are risks in everything we do. But there are some things that we can do that will enable us to see (measure) the extent to which we are succeeding or not.
If you are starting a website, then make sure you have google analytics on your site. It will give you (free) statistics on how many people are using your website, how they got there (where they have linked from) or typed in the address directly.
It will (most crucially) let you know which search-terms are being used on the search-engines to lead people through to your site. Take a while to get to know Analytics quite well. Your new website may not be (yet) generating lots of revenue but you will be able to see its potential to grow, sometimes it will be evident on a week-to-week basis.
The underlying trend should be detectable; giving you a better idea as to how successful it could be in the future months and years. It may be too difficult to tell from your turnover of money whether or not you have underlying growth.
Econonmic fluctuations and seasonal trends can make it a difficult thing to gauge. Also, if you're using google analytics, then you will have the ability to annotate (put informational tags on) any particular day or week that is not normal.