It's not unusual for brides to have a strong vision of what they want for their special day. It's not, though, always easy to incorporate everything. You might be able to see what you want, however what you find can be a little off the mark.
The difference with my girl, and others who share her artistic and creative abilities, is if they can't find what they're looking for they have no trepidation about using those talents to make it. For example, after perusing endless websites and books for the right invitations, etc., she decided the only way to please herself was to design them herself.
Taking some images, tweaking them to match what she envisioned was all it took to get the style she wanted. And with online resources linking us to a vast inventory of images it's made it a lot easier for all kinds of people to try their hand at these types of projects themselves.
However, an image is often only part of the equation. You need words to invite, to thank, to promote, to explain. The best design with the best picture can be ruined by the wrong font. Here again, there are many to be found online so getting something that represents what you need is easy. Yet, as my daughter would tell you, the best way to get exactly what you want is generally by doing it yourself. Here are some tips for creating your own fonts in Photoshop:
eHow Create Fonts in Photoshop
wikiHow Create a Font
speckyboy's Beginner's Guide to Making Your Own Fonts
Create a Custom Font
creativebloz Design Your Own Typeface