I get to talk to a lot of people about websites. As a web developer, I am always surprised by how much people self censor their ideas. So this posting, hopefully, gives you some idea on how to communicate with a developer.
Don't be afraid to ask for things that you feel may be impossible or expensive:
I often find out, after I've done a lot of work on a project, that the client really wanted some feature, but was afraid to ask for it, since they were worried it would be too expensive. With the modern tools now available, it is amazing what can be done now, for far less effort than it used to take. Don't be afraid to tell me exactly what you'd like, and let me tell you if it is impractical. Sometimes it can cost no more, or even less, than some "conventional" method. Just understand, that sometimes, things that you think are simple, could be excruciating difficult. But let your developer tell you what can and cannot be done. Don't censor yourself.
Please predict the future:
When you tell me about your web development or web design project, be sure to tell me about any additional features or functions that you'd like to add in the future. If I know your plans, I can design the site to easily accommodate them in the future. But if you tell me after I've finished your site, it may be much more expensive to do. If I've designed the databases and code with the knowledge that some feature will be needed soon, I can sometimes do that preparation with no extra cost. It is similar to telling your contractor that, in the future, you might want to add a suite in the basement of your new home. He can lay out the conduits and rough in plumbing for a few hundred dollars. But if you wait until after the concrete is poured and the walls are finished, and then decide to add a suite, it could cost you thousands of dollars, and create a terrible mess.
Please supply me with your artwork and copy before I start:
I really want to give you the perfect website, but if I have to use dummy copy and "place holder" images, it won't look as good as if I had the real copy and images available. I can use your images and copy to inspire the site design, and customize your site to match the content. Delays supplying copy and artwork can slow down the project, and stifle the creative juices.