Some recipes call for an exact amount of an ingredient (think baking soda in bread). Other recipes use ingredient lists as a sort of guide. If you're just getting started in the kitchen, it's best to stick to the recommended amount of any ingredient. You may not do it forever, but these measuring spoons will get you cooking and baking quickly.
Measuring spoons should never wear out - as long as you invest in a decent set. Opt for a stainless steel set, like these babies from Cuispro, so you can toss them in the dishwasher an keep them forever. Stay away from the plastic measuring spoons if you can. They're not as hygienic and wear out after awhile.
This particular set also features an oval shape which is particularly useful for reaching into spice jars. (Try to avoid wider spoons if these particular spoons don't turn you on.) Also, you'd be wise to keep everything on the ring and wash the entire set at once; separating them just means that you won't find the 1/2 teaspoon when you need it.