An effectively designed kitchen is one that makes the most of the space available whilst also providing a well coordinated decor theme - be it contemporary, farmhouse or retro. This includes matching up the designs on the cabinets and shelves with the colours of the walls and flooring, and indeed the materials that are used for the construction of each, and can often be achieved by buying a full kitchen suite complete with tiling or vinyl for the floorspace.
Unfortunately kitchen suites are rarely good value for money, and can often run in to the thousands if you're looking to buy a precoordinated, predesigned room from a furniture retailer. Of course that doesn't stop less savvy people from buying their kitchens and labour from the retailer, and ending up paying off what they're due over the next ten years. What that means is that for the buyer on a budget, style, fashion and a little bit of hard graft are going to play more of a part in getting the right kitchen design for your space, and achieving good kitchen design overall.
An alternative way to buy a kitchen that doesn't cost the earth is to buy flatpack and install yourself. Of course this takes time and a bit of work on your part, but by opting for this rather than pre-built and installed units, you could be saving yourself an absolute fortune on your next kitchen purchase.
Whatever kitchen you opt for it's important to make sure you choose matching or complimentary accessories to highlight the colouration in the room. Of course this will vary depending on the style you have chosen, but make sure that the colours work and the shapes and textures fit. Also, make sure you push cabinets flush against the walls and that there is as little as possible to clutter the floorspace. Floorspace is a premium in any kitchen, and good kitchen design will maximise the room available in order to allow greater movement and enhance usability.
Good kitchen design is, in essence about common sense. Think about what you use your kitchen for and how busy it can get to work out the space requirements, whilst stylistic features are very much down to individual taste - just don't make the wallpaper too garish as to put-off any prospective buyers later down the line!