There are lots of factors that go into a successful marketing or promotional campaign. However, when you boil it down, promotion is often founded on aesthetics and specifcally the visual impact of your promotional materials. This is especially the case in regards to banners, which need to be optimized on an aesthetic level.
Of course different marketing environments will put different pressures on your banners to stand out. For example, in an exhibition setting, banners will have to perform above and beyond the call of duty to reach customers in a distinctly competitive environment.
In such a competitive environment as an exhibition, it is important that your banners at once attract your customers attention, whilst not overpowering the visuals of your stands. Therefore, in an exhibition, your banner should correspond to the rest of your , and be matched in terms of colour.
In more traditional promotional settings, such as outside of a shop, banners often have to perform on their own, and therefore the aesthetics of a banner in this kind of environment need to be bold enough to catch a customers attention. You might consider features such as large format printing or , which will increase the visual impact of your banner considerably.
As the rules regarding effective promotion are well known, in order to ensure your success with a banner you will probably need to introduce an element of the creative into the display, which will ensure that your customer's attention is caught.