I used to teach writing and nearly EVERY single one of my students would say "I don't have a thing to write about". Then I'd ask them a few questions about their lives and each one of them knew how to do something or had done something special. One woman had spent nearly two months sitting by her baby's side in an intensive care unit.  A guy made his own fishing lures and could describe most of the newest lures on the market, as well as some vintage ones. Another person had won an award for her apple pie. Someone else had spent 20 years in a  particular job.
    Each of them had seen, felt and learned something that could be taught to someone else .
And that is really all an Ebay Guide, Review or Blog is - passing on what YOU know about Ebay or some particular part of Ebay  or a specific skill - to someone else.
        If you are afraid you'll seem silly or write poorly, don't worry. Just break the process into some simple steps and you'll be fine:
1. Pre-write: List anything you know how to do well, from changing oil in your car to saving time on the job. Don't worry about complete sentences or anything else at this point. Think about what you care about, what matters to you, what you like to talk about and your hobbies. Pretend you are talking to someone who has never done something you know how to do, whether it is baking brownies or teaching someone to swim.

2. Break it into steps: For example, if I was trying to tell someone how to write a listing on Ebay, I might think of these steps: Accurate description, good photos, clear sales policy, shipping terms, etc. Then I could list them in order of importance. Include photos to lend interest and break up the steps. For instance, if I was writing a guide on pet photography I might include this photo:
                
and then I would add something about how the photo related to my guide.

3.Mention something about your experience that grabs the reader's attention. If you won first prize in a National Cooking contest, say so. If you've homeschooled eight kids, that might make someone want to read your guide on Homeschooling Tips.
SAFETY TIP: Be careful about including photos that show the interior of your home or your children's faces. Play it safe in cyberspace.

4. DON'T assume you have to have a "title" or "award" to write a guide. Some of the best ones I've read were written by people who simply had a passion and wrote clearly about it, with some solid photos. Most included a bit of the writer's personality. Some were funny, others were matter of fact. Don't strain to find your style or voice but don't be afraid to let it shine a bit.

5. Which brings me to the next point. If you don't feel like a strong writer, think in pictures. Include those pictures in your Guide. Some great guides use very few words and lots of photos. For example, if you were writing a guide about good photos for listings, you might need to include very few words but plenty of examples of good, clear photos like this one:

and then you might want to include an example of a photo that isn't as clear or doesn't show your item to best advantage.  I've seen quite a few guides here that are 100 words or less or only 6 sentences long but full of photos. So play to your strength and if you have more confidence in  your photography skills than your writing skills, try to "write" in photos and leave the description to a minimum.

6. Have fun!