How to Approach a realtor

[Ruth Towouh]

Good morning everyone, this is my first ever post. I'm new to Real Estate and just started working with a residential investment company in Houston Texas. I like working with realtor in regards to off market listing they're working on, I've purchased a few through them. I'm still struggling with finding the best way to make first initial contact and ask them to work together, some of them are open and most already work with a handful of Investor. What's the best approach to contact realtor and build some form of relationship where they're sending you their listing before it hits the market?