Welcome to RS, Isabella.
I'm afraid your question is a bit too broad for me to give you a helpful answer. Are you seeking to market products that you create? Resell for someone else? Are we speaking of an online business... or a brick and mortar store? I presume online, but people do use the internet for offline marketing ideas.
A number of people choose to go the affiliate route as it often costs very little out of pocket. You can usually get yourself a domain name for less than $10 and find reasonable hosting for not much more.
All businesses fail for one of two reasons:
- Money
- Knowledge
In the absence of either, your business venture will not succeed. I mentioned above that affiliate marketing doesn't require much initial investment, but working capital does help immensely. Don't be afraid to invest in work. For example, paying a professional to make a site or logo for you will often be much more valuable in business earnings than the amount you saved by doing it yourself.
That brings us to knowledge. Like any business, you will not succeed unless you familiarize yourself with the inner workings of your industry. Lucky for you, the best way to learn affiliate marketing is to just dive right in. You've started out by coming to one of the more helpful forums for internet marketing.
Also remember, I think one of the top reasons people fail at their business ideas is that they don't select something that intrigues them. For example, someone who enjoys flowers would make a much better florist than someone that kills every plant they touch (like me). Try to keep your work directed in favor of your interests and you'll find yourself way more successful. I mention this only because you don't seem to have narrowed down what it is you want to pursue.
If you can respond with more specific details of what you're hoping to accomplish, I can probably give you more useful information.