Possibly the "O" rings on the low pressure fuel lines.. Eventually they compress and are no longer a perfect seal
Usually though, this don't so much leak fuel out, as let air in. This causes cold starting issues as the engine needs to re bleed the air from the system after being left stood over night.
Look under your bonnet and try to at least narrow down where the leak is from.
We are not psychic.. (Well I'm not)