
Don't wait for too long before getting in touch: Although it makes sense to wait until the holiday festivities are over and people are back into business mode, don wait for too long after the end of the holiday season to get in touch with your new contact. The longer you wait the lower are the chances that your new contact would remember meeting you. Also, when you meet the new contact the next time, don't expect him to remember you. Remind him when and at whose place you met and a bit of the conversation that ensued. You could even mention a shared interest that was discussed at your first meeting.
Make New Year's greetings an excuse to get in touch: The onset of the New Year gives you the perfect excuses to send an email or a greeting card with your wishes. You could start the email with some greetings and follow up with expressing how much you enjoyed meeting him/her, and can end by stating that you hope you get a chance to meet up soon and talk further on a shared interest. This is a standard New Year's message and has very few chances of going wrong. If the new contact enjoyed meeting you as well, this could well be a start of a good personal or professional friendship.
Add the new contact on a professional networking site: A professional networking site such as LinkedIn is a perfect way to keep in touch with your new contact as it is neither too personal nor requires your contact to put in a lot of his time or effort in staying in touch with you. The two of you can see each other's updates and have more topics to talk about or even notice that you have a lot of friends in common.
Think twice before becoming a pest: You have just met this new contact; wait a while before you ask them for introductions to other people. And if in case you already have, give him a good amount of time to respond to your request before you follow up again. Give them a good reason to help you and thank them for any help that they may offer. You may ask them out for a coffee or a drink, your treat of course, but don't expect them to have time for it. If they say no, don't take offense or keep pestering them for it. Always respect their space and be humble.
Share helpful information: One of the best possible ways to keep in touch with a new contact is to share information about events that the other person may find useful. For instance, if you hear of an interesting professional event, share it with your new contact and invite him to it. Becoming a source of valuable and relevant information will ensure that your new contact will also make an effort to stay in touch with you and help you out in the future if and when you may need his assistance.