Use a couple search engines and see where your ePublisher turns up on the list. Check if the ePublisher offer formats compatible with handheld devices, such as the Palm Pilot, or formats compatible with dedicated handheld eBook reader devices, such as RocketBook or SoftBook. Ask other writers if they've heard of the ePublisher or have had any experience with them. Listservs, either writers' or ePublishing, are good places to ask about ePublishers. Once you've selected an ePublisher, you're ready to submit your manuscript.
Competition is tight.
The quickest way to rejection is to ignore the submission guidelines. Sloppy manuscripts or presentation are quick routes to the rejection pile. Edit and proofread before you send. New ePublishers have a fairly quick turnaround time, but as more manuscripts are submitted, response time will slow down. Often the Guidelines will give estimates on response time, and suggest when to inquire.