There are many hosting companies that start out thinking they need to "jump" right into a dedicated server. Thats not really the case. Reseller packages have basaicly the same thing with the added benefit that there really isn't that much work for you to do, espically with a management system such as cPanel and a reputable host taking care of the server.
The most important thing to look for is a host who has been around for a while (I'm not saying in the top ten on a google search - but its probably not a good idea to sign up with someone whose domain name was registered a week ago). If you can find a decent provider (and there are tons of them out there) a reseller package can be wonderful.
Perhaps the one important thing that you would want to look for is a hosting provider that not only has good reliablity and service, but an easy way to upgrade your package should you need additional space.
Another important thing would be to see what type of self-help resources they offer and whether or not they would be willing to let you use those on your site to help your customers (many hosts are actually willing to let someone use this information if they only ask).
Of course, along similar lines, many large hosts have pictures of their data center and don't mind if you use those pictures on your own site - technicaly not really cheating because the server is there (but I definatly see how it could be considered a somewhat immoral ploy).
As to specifics, stay away from anything that is unlimited. Figure what your prospective clients would need, figure a decent estimate of how many clients you can acquire in a month - start with that - estimate on the low end (you can always upgrade later) and there is no sence in wasting money until you have the customer base to at least pay for your own hosting / reseller costs.
As to the different systems, many customers seem to want Windows servers because of ASP. You might want to try to find a host that actually has ASP on their linux servers - one of the main reasons for this is that many of the linux ASP programs are commercial (and rather expensive) - so you atleast know the host has some money that they have invested in software.
Of course, you will also see control panels ranging from cPanel (popular with linux), Ensim (popular with large companies for some unknown reason), Plesk (nice, but you have to pay for all the nice added features), Helm (*shudder, bad memories*), as well as a plethora of other "custom" control panels.
cPanel is by far the most common and has a great reseller control system built into it and its what I'd recomend (at least in a Linux hosting environment). Second recomendation would be Plesk, then (saddly) Ensim. Although some of the customer control panels are nice - you'd have to be very careful to make sure that its not one of the ones like WebMin (Open Source, desgned to make running servers easier, not a good customer/reseller interface at all).
Well, help that tid bit helps someone....
smartin [at] nocturnalhosting.com
Yeah.. when starting out, never jump right into a company without thoroughly researching them first. I made the error of jumping right into levi1.com back when I first started. Dear god what a mistake that was. This was before I knew that forums like this existed, though. Communities like Hosting Discussion provide amazing resource for web host research.
Don't make the error I did! User reviews are where it's at. Dig as deep as possible for any dirt on a potential host that you are considering opposed to jumping in blindly. It might just save you from getting scammed.
__________________ Matthew Z
Stimulated Vulcan MJZ Web Hosting - The ULTIMATE budget hosting solution.