The first and most important thing to do is to list all of your skills. What skills do you have? You may have picked up these skills through daily life (for example languages), through your job (hands-on knowledge on a specific niche) or from your hobbies (for example fishing). It is most vital to list down skills or knowledge that you have and might be in demand elsewhere. For example, you love fly-fishing and you do it every day after work. You may build your Internet business upon this: writing an instructional guide on fly-fishing, teaching people how to do it, etc. Best of all, you do not need to spend money to acquire this knowledge: you already have it.
So, the very first option, if you have no money to start your on-line business, is to earn some capital using your already existing skills or knowledge. You can give tuition to students in your dominant subject in college, you can teach stuff about your hobby to people who are interested, you can write guides on knowledge or skills you have picked up through experience and cannot be found in theoretical books.
Okay, let's say if you just can't think of any skills or knowledge that people might be interested in. Then, it's important that you locate a workable business model and focus on that alone. You can obtain almost everything you need through bartering, web hosting, domain name or credit card processing, to name a few in exchange for your product (if you own one) or services like copy-writing, ghost writing and website designs. There is always some mundane job that people don't want to do, and you can do that for those people in exchange for things you need. You just need to ask for it!