Keeping all of the marketing elements cohesively designed helps to translate the vision you have for your business to your clients.
I'm often asked about how to make a collection of marketing materials and web elements cohesive. Is it even necessary to make them have a similar feel. The short answer is YES! While the various design elements of your branding do not have to be identical, there should be a similar theme to the entire package. In short, you could have the exact same red rose on everything related to your brand marketing, but it's not necessary to still have a cohesion to the elements.
In order to achieve cohesiveness without necessarily using identical images for instance, a good course of action is to stick with a theme. As an example, if you have some type of floral element in your logo or website, add a similar type of flower to the other areas of your marketing. Try to stay in the same family of elements. So you wouldn't do a rose and a fern. 😉 But perhaps you could do a yellow rose on one element and a pink rose on another. Another example would be if you use some type of clothing piece, say a straight tie for one piece of your marketing arsenal, you could use a bow tie for another element. Same theme, different imagery.
Another very good way to incorporate themes across marketing elements is of course with colors. And your colors start with your logo. It's very important that your logo have a set in stone color palette that is carried throughout all of your marketing. But the color palette can have several elements to it. For instance, if your company/logo colors were blue and green you may make your brochure have blue and green accents. The text may still be standard black and the paper color may still be white, but your brand takes center stage by infusing your brand's color palette in other areas like headers or background imagery. Another example, your website could have green header text and maybe a blue background for the footer, or vice versa. Keeping a consistent color scheme throughout all of your marketing helps to make your brand recognizable and of course, cohesive. Make sure that whoever designs your logo provides you with a spec sheet that outlines the codes (HEX, RGB, CMYK, etc) for your colors. This allows any other designer, printer, etc to make anything you need for your marketing and have all of the colors be identical, even if the same person doesn't make the product.
Your brand has to feel like it's intentional, professional and most of all, that it reflects the nature of your business. Keeping all of the marketing elements cohesively designed helps to translate the vision you have for your business to your clients.