Based on the information contained in the question, my involvement starts with:
1. Get agreement to be EXCLUSIVE sales agent while in construction
2. Become the listing agent upon completion.
3. Bring a buyer before someone else does.

Of course you question may pertain to representing a buyer in a new construction situation.

I have had occasion to introduce clients to new developments in which they made a purchase. In all cases, the representative of the builder took control of the transaction, completed all the paperwork and legally represented the buyer as well as the builder.

I was paid a referral fee.

New construction was my main meal most of my career Jadden Cranney . If you set out to represent Developers, builders, and contractors you will have a great career. Keep in mind they won't come to you and you need to provide them a special service unlike your typical seller. Once you figure it out you won't want to work with random clients again.

I bring them buyers and collect my fee.

Jadden,

We just complete an enormous marketing campaign for a $100 million dollar development.  A

I list and sell new homes. my largest community i listed was 149 homes. Right now we have a shortage of new construction and i could sure use some more to sell. 

We have build homes and garden apartment communities.

Currently I am not however been there and done that. Very lucrative

buyer agent

Buyer representation

The same as any resale. If they offer compensation and a quality property, I show it!