I have always saved and uploaded my illustrations as JPEG's because I don't really know how to do the whole EPS stuff. I make all my illustrations in Adobe Photoshop, so they arn't exactly vector, they have lots of gradients and such. I have tried importing the .psd file into Illustrator then saving it as a .eps but the file size is almost always over 100mbs. Am I doing something wrong? I see vectors up that are more complex than some of my work that always ends up being over 100mbs. Please help.

Example of something I have tried making into EPS that resulted in 180mb file:

OK well I got the answer I was looking for. Turns out it isn't possible to convert them into vectors efficiently so I'm just going to pass on doing it. 
I make my JPEGs absolutely huge anyway. (usually at least 20 megapixels)
I'm getting a decent amount of downloads with just the JPEGs.

If you just imported that image into Illustrator and then saved it as .eps, you would not have a true vector. There are a number of stages to go through to make it a vector.
To see how the paths work, try opening a new document, click File, then Place, and put you picture into the document (Better resize it to about 600 pixels first)
Then click on Trace, and then Expand. You can now see the paths that make a picture a vector rather than a jpg.
Autotraced images are not accepted on a lot of sites because they are usually a mess, with loads of confusing paths. You need to use the pen tool to create accurate paths.
Drawing in Illustrator is not like drawing in an art package, it is a totally different approach.