It's pretty erratic, at least for the next 6-7 years or so. Here is a list of the opposition dates between the Moon and Venus when from some parts of the Earth, the Moon will eclipse Venus:

4/7/97       New
3/24/98      Last Quarter
4/23/98      Last Quarter
9/19/98      New
3/4/00       New
8/1/00       New
7/17/01      Last Quarter
12/14/01     New
5/14/02      New
5/29/03      New
10/26/03     New
5/21/04      New

If you look around the 'First Quarter' dates, the Moon will be close enough in most instances for a pretty picture. I do not have any convenient tables that pinpoint conjunctions for whih the crescent Moon is to the North or South of Venus, but the above opposition dates should be good starting points to watch for.