People will feel more comfortable if they can relate what you are saying to something they already accept. Once you have gained their trust, they will take what you have to say more seriously. This is necessary in order to be understandable and look professional. Don't always worry about proper grammar. Sometimes it is necessary to use some poetic license in order to make your copy easy to read.
Short sentences deliver impact.
Short paragraphs make the copy feel less overwhelming. Internet copy writing that is warm and friendly, light and snappy will work best. And, don't be afraid of a little levity. The interactive nature of the Internet offers you a unique opportunity that can work for you or against you. Take advantage of what this new environment has to offer by personalizing your online copy.