Close-ups of textures can make interesting images on their own but they are most useful for blending with other images to add interest to plain backgrounds or to give a particular shot a different look / feel. Towns and cities are great places for hunting down textures and once you start looking at detail rather than buildings as a whole, you'll soon find a variety of textures to fill your memory card with. Walls, steps, doors, sheds, modern metal structures, roof tiles and windows are just some of the locations you'll find interesting textures at.
When it comes to kit choices for this subject, zoom lenses are useful for selective cropping while a macro lens will get you close to the patterns you're capturing. Pick up a telephoto lens when you want a tighter perspective. A tripod is handy for when you're using a telephoto lens and will also help ensure your shot's straight. A remote release or the camera's self-timer are tools you'll be using quite often, too.
Subjects that have a pattern that repeats such as a brick wall or the lines found in wooden planks and doors look great but don't think they all have to be symmetrical. Having a variety of colours and lines can work well especially if you have two contrasting objects to work with. Try to find somewhere new buildings meet old and see if any of the strong metal structures overlap or cross the older, softer structures. Head out after it's rained too as surfaces take on a different feel/look when they're damp and covered in water drops.
Don't zoom in too much as often a shot that's taken with a little more distance between you and the subject will look better and that way there's always the option to crop the photo when you're in front of your computer back home.
If there's a distracting object, shadow or mark in the frame either move your feet to find a different angle or use your zoom to cut out of the frame. Try shooting straight on to make your texture as flat as possible before moving on to experiment with different angles as these types of shots are often great for adding to other images and the flatter the surface is the easier it is to use. To emphasis the shapes/textures position yourself so your light is on one side. This will create a strong shadow and give your shot extra depth.
If you're working on a new building watch out for glare and reflections which can easily be removed by simply moving your feet a little and finally, pay attention to your white balance as you may find the cloudy or shade options produce better results.