How do I find people who are into flipping homes to build clients? I'm on BiggerPockets but is there networking events or other sites I should be active in?
When you download your data for your mailer in a particular zipcode, there will be a bunch of LLCs, Partnerships, Trusts, etc. each of whom own multiple homes in that zipcode. Some of these will be landlords, but many of them will also be renovators. THAT is your list. Contact them directly and invite them to your open house when you get your first deal, or meet with them before you mail and ask for their buying criteria and mail to that if it meets your numbers.
In terms of meeting people face-to-face, most urban areas have groups you can find on meetup.com. Find real estate clubs there and attend. However, most of the people there will be newbies to some extent. Find a club that is not a guru presentation/funnel for more newbies to sign up for their particular brand of whatever they are selling. Also, once you find a club you like, my advice is to stick with it and develop relationships. I've found TONS of great help from members in these clubs, but really only once I showed up consistently.
Hope that helps!