The best hair care advice I can give is for any hair style you select, you should have your hair cut specifically for that style. It is possible to have a convertible hairdo, one which can be worn in two or more ways, but I do not recommend it. When the hair is cut to conform to a certain shape, it's illogical to expect it to look right in other shapes as well.
The reason for cutting hair in the first place is to shape it. It's like cutting material for carpentry, sewing or any other form of handicraft: you cut your material to measure. When cutting lumber to make a piece of furniture, you cut each plank to the precise length needed for the construction of that piece.
You can see how ridiculous it would be if, in building an automobile or a boat or any other object, the worker failed to cut each part to the exact size and shape required and instead left the excess material trailing off the back or sides. Shaping hair can be regarded in the same terms.
It is even more important, in fact, to have hair the right length for each individual change of line. An error in cutting fabric, for example, might not be so serious because it might be able to support itself or be given support. Hair, however, is a substance that must hold its own shape, and must be cut in a way that will enable it to do so.
I believe, therefore, that in all cases-outside of some very slight changes-hair will always look best and fall best when it is set or combed in the way for which it was cut.
A Year Without A Haircut
Here is some hair care advice you may never have heard before. It is perfectly possible for you to go for a whole year without a haircut, by adopting a style that changes as it grows, but always in a pretty and becoming manner. The style is one that achieves its beauty through simplicity of line and clean, shining hair and the knowledge that hair grows half an inch a month. An example of a suitable style would be a short straight pageboy with a very short bang. The bang may be actually cut right to the hairline or about a quarter of an inch below.
Six weeks later the hair will have grown three-quarters of an inch. The bang can be cultivated into a longer straight bang and the ends into a slightly longer pageboy. Three months after the original haircut the hair will have grown an inch and a half. Now is the opportunity to turn a fairly straight hairdo into a fairly curly one if you wish. The bang, which is now an inch and three-quarters, can be turned into a wavy bang. The ends can retain the pageboy contour or can be fluffed.
At the six-month mark the hair will have grown three inches all over the head. The wavy bang now moves to the side. The bottom hair can continue as a pageboy or with fluffy ends.
Between this point and the end of the year, the hair can be worn long and loose at the sides or it can be pulled back into a chignon, a pony tail or a cluster of curls. The former bang is brushed back to join the sides. By the end of your year without a haircut you have an entirely different hairdo from the one with which you started, and will have enjoyed the interest, the variety and the economy of letting it grow according to plan.
So my considered hair care advice to you is style your hair in the way for which it was cut, and also, just for an experiment, enjoy a year without visiting your hairdresser.