Parker suggest that graphic designers embrace a few qualities that will result in an effective and attractive design. The designer should practice restraint, concentrate on proportion, balance consistency and contrast and pay attention to detail. Lester suggests four design concepts to consider: contrast, balance, rhythm, and unity. The more time spent on planning, the better -- it shows in the quality of the final production and the time saved during its creation. Planning should be done on paper and include a clear and precise specification of objectives and purpose, an analysis of the intended audience, and a definition of the content to be included. Simonsen and Kensing suggest using ethnographic techniques to address audience analysis. Planning should include considerations of overall graphic design and color schemes and carefully chosen opening and ending sequences, designed to introduce the subject and to summarize and tie it together. Clean, attractive titles should be developed for each section. Material on the screen should be kept to only a few lines, with large text, and only a few words per line. Key phrases are more effective than complete sentences. Bulleted or numbered lists are quite effective. On a screen, simpler, less cluttered design is more effective. The choice of images is extremely important. A poorly chosen image can be a distraction rather than an enhancement in the delivery of a message. It should not compete with the main message of the screen, and distract from that message. Usually one or two fonts and type sizes are sufficient to distinguish levels of ideas; additional fonts or sizes only distract from the message and may confuse the user. Type size should be used to indicate the relative importance of material; the more important it is, the larger the font. Simple block and sans serif type fonts are generally easier to read. Hyphenated lines tent to interrupt the continuity of a message and should be avoided. It is important to spell-check and proofread all text as a simple error can detract disproportionately from the message and spoil the overall effect. Except for photo-realism, the choice and range of colors used on a screen should be carefully considered and probably limited. This is especially important if it is going to be viewed through a web browser. Th number of colors of text and/or monochrome images should be confined to two or three displayed on a plain, contrasting background. Bright colors should be used for the foreground; pale colors should be used for the background. The more important the message, the brighter the color. Some colors, such as bright red and bright green may clash and cause eyestrain when displayed together.
Shneiderman's eight golden rules of dialog design: (1) Strive for consistency; (2) Enable frequent users to use shortcuts; (3) Offer informative feedback; (4) Design dialogs to yield closure; (5) Offer simple error handling, (6) Permit easy reversal of actions; (7) Support internal locus of control; (8) Reduce short-term memory load. User interfaces should be as simple as possible. For use of natural language in a HCI dialog, several classes of problems must be addressed: human speech must be recognized and understood, and the computer must be able to construct correct and meaningful phrases.
Developers must always keep in mind the possibility of user and system errors. The first design objective should be to prevent the errors from occurring, the second to minimize their occurrences and the third to provide the most useful error message and the most graceful, lest disruptive opportunity to correct it and never be condescending. KISS is the key. Fields, Wright and Harris classify user errors as omissions, substitution and reversal. Neilsen suggests four simple rules for constructing useful error messages: (1) They should be phrased in clear language; (2) They should be precise; (3) They should constructively help the user solve the problem; (4) They should always be polite.
A truly intelligent interface is on that accepts complex input from the user, interprets that input in context, accesses some form of knowledge base, and produces an appropriate, meaningful response or result for the user. This is a major undertaking. Tanimoto points out two areas that may cause limitations in intelligent interfaces: the quality of the knowledge base and the speed of the inference engine. A third limitation is the degree to which the inference engine can be context-sensitive.
Hypertext is a body of written or pictorial material interconnected in such a complex way that it could not conveniently be presented or represented on paper. A browser is a tool that includes navigation aids such as: active table of contents, backtracking and history lists, bookmarks, guided tours, maps or web viewers, and timestamps.
Berners-Lee et al point out several aspects of the Web: Whatever type of server, the user interface is the same; Links can point to anything that can be displayed; There is an extendible system for introducing new formats; there are many browser programs. Siegel says these "sins" should be avoided: (1) Blank line typography; (2) Horizontal rules, (3) Background images that interfere, (4) The slow load, (5) Illegal use of the third dimension, (6) Aliasing, dithering and halos; (7) Paralysis.