In Product Management: Ajay Sharma voted up an answer.

The holy grail you'll hear about this type of question is to "know your customers and have the data to back it up." If you have that on your side, you can convince the engineering organization to follow your lead. Then, provided you are right, you'll reap the benefits in successful features and product, which in turn gets you their respect.

However, that is — in my experience — a utopian model. It is rare, many times, to have that pivotal piece of customer feedback or data driven evidence needed to justify your position. Things move too fast to have predicted every eventuality and done all the homework needed to make that rational argument. When you're just starting out or in a small organization, it is even more difficult.

So some alternative things that can help:

1. Have the visual, verbal commitment of your CEO (or analog in your company). If they know you're their voice, they will tend to listen. You will still need to earn respect through your track record, but this helps a TON.
2. Prove that you are a buffer. In bad organizations, engineers routinely will feel they're being pulled in a ton of different directions. If you can be a source of positive momentum and removing the distractions that end up in their world, they'll appreciate you. Engineers are — as Rands has taught us — volatile to distractions. They like to enter the zone, so you're protecting their zone and therefore you are their friend. You get it.
3. Avoid buzzwords. That'll get them to snort behind your back. Don't talk about social media, virality, synergy, fusion, or other "nothing" words when describing a feature idea. Instead, talk about how this helps the user. "This increases the virality of the content they create" sounds lamer and like you are just making it up as you go than "This pushes their content onto two new platforms, where there is on average 40x more reach, while keeping them from having to spend an extra two hours a day doing it their current way."
4. Think like a Vulcan. Engineers respect logic, even if sometimes your decision is emotional.
5. And be honest. Even if you represent the CEO, you don't have to be a "suit." When you don't know, admit you don't know and that you guys are all taking a gamble together. That builds empathy and buy-in from them.

As for communicating, aside from the above tips:

1. Be fast. Be clear. I think it is SCRUM that ascribes that any engineering decision needs to be made within 20 minutes of the question's formation. This is an extreme example, but the more decisive and quicker you can answer a question about a feature the more likely you are to both get what you want and for the engineer to ask you the next question (rather than making it up on their own).

See question on Quora