Assume you know more than the client

Introduction 
Talk a lot about your agency history   
Assume you know more than the client 
Forget the client's budget constraints 
Be oblivious to the client's other agencies   
Ignore the RFP 
Staff the pitch with who is available 
Conclusion

Why do so many agencies assume they know more about the client's business than the client? You wouldn't go into a sneaker company and tell it how to design shoes, so why do online agencies go to brands and insist on what they could do to improve the product?
 
Many agencies get excited when researching the client's brand while preparing for the pitch; excited that they are going to discover some unique insight that the client has not thought of. They get excited when they experiment with the client's product and discover nuances about it ("if the product could only do this…"). It's tempting to go overboard when acting on this excitement, but do not fall into that trap.
 
The client knows who their consumer is, and probably even knows who it should be. On the other hand, your knowledge of how to influence the consumer is what's important to convey. Your challenges are the same as the traditional agency: finding out what the challenges are to consumers adopting the client's brand and its products. It's your job to develop programs to get those consumers in the door. It's the client's job to have a product good enough to have them come back.
 
Most clients understand the current limitations of their product and the challenges to consumer adoption. They usually have a product roadmap planned for two years out to fix those issues. If possible, ask them what success looks like to them before you present. That will help determine what they believe will help move their brand forward. Does it involve tinkering with their product? No? Then you will have to leave it at that.
 
Bottom line: Do not recite what, to them, is obvious about their product.

Next: Forget the client's budget constraints