Just did a similar task. I started off with a 65 gallon freshwater tank. I totally cleaned it out and washed it with water, vinegar and a new sponge. Fill up your tank with Reverse Osmosis water, it's worth it. You can get it in 5 gallon jugs. Let it circulate through your totally clean system, including pumps, heater, powerheads. Get a good book and do some studying. Now that you know how much of each to get, buy yourself a protein skimmer, powerheads and upgrade your lights. Maintaining proper temp is very important so I went out and got a new heater aswell. Put it all together and add the Marine Salt Mix to the water. Let it run for a good 24 hrs and take your first water readings, salinity etc. After about one week I added 90 lbs of Fiji live rock to my 65 gallon tank, so double that, then add the type of substrate or sand that you want and let the tank cycle. Leave the lights off. Mine took about 1 week. Once your ammonia, nitrite and nitrate are at 0 you can add a cleaner crew, crabs and star fish, and I added 1 royal gramma and 3 highfin Cardinals. Also, I suggest 10% water change every week. Remember to age your replacement water. It's worth all the work, have fun!!