Speaking with some experience (Score 1)

I've ordered and installed hundreds of SSL certificates (usually one or two a week). We use GeoTrust for nearly all of our certificates and I have never had any sort of problems. Their turn-around time is very fast too, at least in comparison to VeriSign and Thawte. Probably the easiest thing you can do to ease the process of ordering certificates is to make sure your domain WHOIS info is up to date. But really, as long as you know what info you want to have on your cert, there isn't much to getting one ordered.