The best advice for a new free site builder is to submit to at least 50 or 60 for a couple months at least...until they learn who will send THEM traffic. There are some niche LLs and niches on smaller LLs that don't send a ton of traffic, but they're highly targeted.
If you build 6 or 7 mirrors full of the smaller LLs they'll be happy to have the submissions and are more likely to list you, especially when you're still learning how to build free sites. Once you start seeing some sales, check the referring URLs from your sales to start narrowing down who is sending the QUALITY traffic in that niche. I've had mirrors that only got a couple hundred hits a month total from small LLs that still made sales
