If it is a new tank put RO water in and add salt and let it filter for a day before adding LS. This is the only time you can add salt directly to the tank. When you perform weekly water changes of about 10% mix water in a bucket (the bucket should not have been used for anything else) or new trash can with salt and use a power head to circulate it for a few days. the water should circulate for at least 24 hours but 48 hours to a week is better.
For more information in SW check in the archive section of this board.
Also, check the links in the first post in the new hobbiest section.