The first step in Setting-up a marine tank is that you have to decide what type of tank you want. Do you want a reef tank or just fish. The next Step to consider is time factor you can devote to maintaining the tank.  Next you will have to consider the size and location of the tank. When deciding on the location, remember that the tank when finished is going to be heavy. You need to find a place that you know can support a heavy aquarium. How to figure the weight: First, you can find out the weight of the tank by asking the store that is selling it, they should be able to tell you. Second, you need to know what the stand weights, again you can ask the store selling it. Third, you can calculate the weight of the water (gallons x 8.25).   Fourth, add in the weight of the sand. Fifth, add in the weight of live rock, if you are going to use it in your tank. Now you can look around  and find the perfect location in your home or office. Next consider the filter system you want to use. I prefer a wet/dry filter and a protein skimmer. You can also use other types of filters. This is the choice you have to make, because there are so many different way you can set-up the filter system for your tank. I have found that a good wet/dry filter, a protein skimmer, live rock and live sand work great. I have put the heater in the sump of the wet/dry filter. I also put a ground probe in the sump to help stop Hole in the Head diseases. Now you may find another combination that works for you. This is the set-up I have used in all of my tanks. Chemical used to treat the tank, I feel is also important. I use Stress Coat, AmQuel, NovAqua, Cycle, and a variety of Seachem's Marine/Reef Supplements. Now if you are not going to be keeping corals you may not need to add the supplements. I have tried other chemicals to get the water ready for the fish but I have found that Stress Coat, AmQuel, NovAqua, and Cycle work the best. Now I do know there are a lot of good chemicals out there to get your tank ready, so you may find another company's chemicals work better for you. The main thing is just try different chemicals and then use the one you like best. Now that you have your filter set-up ready to go, you need to decide what lighting system you want. If you are going to have just fish, you can get away with just the lights that came with the system. If you want coral then you have a lot of choices to make. I use VHO lights for my tanks and they seem to work great. You can go with Metal Halogen or VHO or a combination of each. Again this is an important decision you have to make. Different corals need different light. If you know what corals you want to have then research what lighting hey need and this can help you make your decision. Ask around and see what other like best. Next, for the first set-up, put water in the tank and fill about 50% and then I start adding a salt mix as I continue to add water. I add water with a hose. I use Instant Ocean as my salt mix, I have found it to be the best again this is up to you on what brand you use. I add one bag per 50 gallons. I also now add the sand that I have picked to use. I usually use a mixture of live and none live sand. Next I add some live rock to the tank. I then stop the water filling when I have about 95% of the tank filled and then I test the gravity of the water and add water or salt to get it to 1.023. I also start the filter system. I now add the rest of the live rock that I want in the tank. Once the tank is at 100% full, I add the chemicals to remove any harmful particles from the water. I let it set for a week or so and then test the water. I use different test, I usually get the test set that is on sale. I also take some water to the local pet store and let then test it as well. I add any chemical as needed. The water quality usually is bad for 2 weeks after adding the live rock, But after 2 weeks it usually is fine. I then test it again and if it is ok I add a few fish, invertebrates, or coral I have selected. This is all up to you on the fish, invertebrates, or coral you add. I do not use damsel to cycle the tank, I have found that the live rock work fine. There are a variety of fish, invertebrates, and coral to add, just read all the information you can and know what you are putting the tank. Some fish, invertebrates, and coral you need to wait on before you buy then. Just ask and research, that is the best thing you can do to help your Marine Life survive. The main thing I can tell you to have a successful set-up is to do research and read read read. Get all the info you can and you will do great.... 

GOOD LUCK!!!!!