In the answer to that question are the seeds to your future success, and also, the answer as to how you should start. If, for example, you think you could take an existing web site and improve the writing, or its organization, you are positioning yourself as a content developer or architect, or, possible, a producer. These aspects of site development do not need the expense of heavy-duty graphics software, etc. But they need knowledge and experience. There's often a wide gulf between what you think you can do and doing it.
Time taken to build experience is what fills in the gulf.
Well, to avoid that situation in the first place, you need to have enough experience to know it can happen and what your options are. If you want to get involved with graphics, etc., you might do a site in exchange for the client funding your purchase of the graphics tools you need to build it. As you can see from the responses you got to your two posts, people are willing to be helpful and share their knowledge and experience. Join the critique list, too, as checking out others' sites and reading others' critiques of them will give you a better idea about what's considered good practice in terms of design and optimized data. If you do have sites you've already built, post them up for critiques.