The best advice any one of us can offer is to take your time and research every piece of your system before adding it. In other words if there is a pump or skimmer you want read about them and ask questions here to get personal experience with each piece of equipment. Also don't always take what an LFS
tells you as law. Most of the time they are just out to make money and will not always give you the best advice.
Pick up a couple of books on reef tanks and SW
systems and do lots of learning. The better prepared you are starting out the easier and better your SW
experience is going to be.