One of the things that's crucial to learning proper hair care is being completely honest about your hair routines and how they effect your hair. Anytime you use a chemical (or a lot of heat) to change the nature of hair, you damage it. Relaxers, texturizers, permanent and semi permanent hair color all creates some type of damage to the hair. Different companies manufacture products with properties to reduce that damage, but it is damage nonetheless.
It's important that you understand and accept this truth. If you don't believe your routine causes hair damage, you won't take the necessary steps to reduce the damage (damaged hair can't be repaired, but that's another story). Once you understand these processes are damaging, you will make better choices about what, how, and how frequently you choose to perform them.
Chemical relaxers open the hair shaft, and make the hair bonds malleable. Once the bonds are malleable, the hair shaft is smoothed, thus rearranging the structure of the hair. When the hair is rinsed and neutralized, this stops the chemical reaction and the rearranged hair structure becomes permanent. This is why it's extremely important that your relaxer applications do not overlap, otherwise you will find the hair repeatedly weakened and degraded where the relaxer applications have overlapped. This is also why it's extremely important to have substantial new-growth before a "touch-up", because it enables a clearer view of the two textures, reducing the likelihood of overlap.
The same applies to other procedures, including color. The funny thing about color is the level of damage often has a great deal to do with how many shades you're lightening your hair. The lighter you go, the more pigment you remove and the longer the application time.
Now that you understand that chemical processes do cause damage, we can give you some tips for taking better care of your hair:
1- Use chemical treatments as infrequently as possible
2- Deep condition your hair at least twice a month (preferably weekly)
3- Use combs with wide teeth and rounded edge brushes (please don't brush your hair 100 strokes like Marsha Brady, either!)
4- Use quality hair care products
5- Throw your hair grease in the garbage (more about that later)
6- Protect your hair from inclement weather with hats or scarves, cover your hair at night with a silk scarf
7- Treat your hair with care