I own a general directory for which i get about 20-40 submissions per day. Just 3 months old. I was wondering when would be the best time to switch from free to paid directory so that i can profit from it. Should i make the directory free & paid or only paid one?
well if your wanting to just make money make it full paid if your wanting to keep your directory an actual quality directory useful to the general web user than continue accepting free submissions and offer and express inclusion option.
When your directory offers good link value and the vast majority of your pages are cached and have PR is a good time to offer a paid option along with free submission. Free submission is vital to a directories development.
You should probably have a transitional period between free and paid. Firstly offer a paid option, when you can guarantee a prompt site review. This will appeal to more and more webmasters when you have a long queue combined with good PR on internal pages. Continue to add sites, but raise the quality bar for free submissions. So the numbers of sites you add should remain steady, but over time a greater percentage should be paid than free, until you are accepting 100% paid submissions.