A logo will make your company identifiable. Using the same, or tonal, colours in your marketing material will make you look like a professional outfit which thinks about what it does, rather than one that just throws things together or chooses the cheapest option. Use your logo at every opportunity to give your target audience an anchor to identify you.
Top tip: Use a professional designer – in this game you get what you pay for. If you pay peanuts to get a monkey your logo will give the impression you don’t care about your company. Pay a professional to get a top quality logo and your logo will show you are serious about your business.