You should ensure that you document policies for your project - remember that it can be difficult to implement quality if there isn't a shared understanding across your project of what you are seeking to achieve. For example, see the QA Focus policies on Web standards and link checking [1] [2].
You should ensure that your technical infrastucture which is capable of implementing your policies. For example, if you wish to make use of XHTML on your Web site you are unlikely to be able to achieve this if you are using Microsoft Word as your authoring tool.
You should ensure that you have the resources needed to implement your policies. This can include technical expertise, investment in software and hardware, investment in training and staff development, etc.
Without systematic checking procedures there is a danger that your policies are not implemented in practice. For example, see the QA Focus checking procedures for Web standards and link [3] [4].
You should seek to provide audit trails which provide a record of results of your checking procedures. This can help to spot trends which may indicate failures in your procedures (for example, a sudden growth in the numbers of non-compliant HTML resources may be due to deployment of a new authoring tool, or a lack of adequate training for new members of the project team).
Rather than seeking to develop quality assurance policies and procedures from scratch you should seek to learn from others. You may find that the QA Focus case studies [5] provide useful advice which you can learn from.
If you are in the position of having deployed effective quality assurance procedures it can be helpful for the wider community if you share your approaches. For example, consider writing a QA Focus case study [6].
You should seek to implement 'fitness for purpose' which is based on the levels of funding available and the expertise and resources you have available. Note that perfection is not necessarily a useful goal to aim for - indeed, there is a danger that 'seeking the best may drive out the good'.
Although the QA Focus Web site provides a wide range of resources which can help you to ensure that your project deliverables are interoperable and widely accessible you should remember that you will need to implement quality assurance within your project.
Rather than seeking to implement quality assurance across your project, it can be beneficial if quality assurance is implemented at a higher level, such as within you department or organisation. If you have an interest in more widespread deployment of quality assurance, you should read about the ISO 9000 QA standards [7].