Iain said this in an interview the other week:
"I guess the dark art is how to influence people to do what’s right, but let them feel like it’s all their idea."
This is a skill you have to learn if you want to get your ideas into the advertising process and you're not an official 'creative'. Your ideas are very welcome as long as no-one knows they're yours.
A good way to do it is described in this story about Angelo Dundee:
"Leaders of all kinds, whether or not they read social science, are alert to the power of making certain abilities and characteristics salient. Angelo Dundee, perhaps the best boxing trainer of all time, had the difficult task of training Muhammed Ali, who did not exactly like to take direction. But Dundee had a brilliant trick: “Every now and then I’d subtly suggest some move or other,” he explained, “couching it as if it were something he was already doing.” For example: “‘My gosh, you threw a tremendous uppercut. That was beautiful!’ But he had never thrown an uppercut.”