In any letterbox delivery campaign, it is important to be clear about what you expect to achieve.
You need to be clear about why you are doing a letterbox delivery campaign. Generally, letterbox delivery campaigns are done to promote your brand, offer people an experience of your product (such as distributing a sample or a discount voucher), or to keep your name in front of people.
Once you know your why, it is easier to then decide what you are going to distribute.
A good letterbox delivery campaign involves multiple deliveries. For example, your first flyer might be an introduction to you and your offering. The second flyer might include a sample or a discount voucher or further information on what makes you different to your competition. Your third flyer will reinforce your brand and what you offer.
The distribution of your flyers should be at regular intervals, such as fortnightly or monthly.
It is also important to make sure that your staff are aware that you are doing advertising. Sadly, many campaigns fail because staff are not trained to deal with enquiries from potential customers. If you are distributing vouchers you need to make sure your staff know how to process them and keep a record of them.