I have started using Kerastase by Loreal - very expensive, but very little required. Check it out. I had thick, coarse, straight, dry, frizzy over processed hair (I'm in my mid 50's now). I had beautiful shiny hair when I was young - I use several of the products and switch depending on my needs at the time. My hair has totally transformed in a year, but I saw results in 2 weeks. As far as splittage and breakage goes, elastics are the worst, a cheap brush, brushing too vigorously when hair is wet = they all contribute - as well as a poor diet and not enough water. For a cheaper alternative, the Pantene line is very good as well - but no comparison to Kerastase. People who complain about Kerastase making their hair 'too heavy' are using too much product.
I have a local salon here in Toronto Canada I can buy from, but I have also ordered from ebay. If you are in the States, you can order on-line. First and foremost, try the nutritive line - I use the shampoo Bain Satin#3, and Masquintesse conditioner for dry hair, then I apply Ciment Thermique before I dry my hair (I use a new ion technology hair dryer - that has also helped to dry hair faster on low heat and beat the frizzies). Then before I use the flat iron (a very good salon quality wide one) I use Lait Nutri Sculpt. Occassionally, I use Oleo relax serum (very very little on the ends)-but I'm not crazy about the smell of that product. My hair is dyed and trimmed monthly and falls to my shoulders, and I also wear pony tails a lot - with special elastics that don't break the hair. I also bought a good brush and brush less often - not more! I have just used Noctogenesist serum nuit - wow - it works really well. My hair is now shiny, soft - still very thick, but the flat iron tames that, - I have had so many comments in the last year from friends and coworkers on how great my hair is that I will never use anything else again. Honestly, it was always the bain of my existence - I feel so much more confidence. A set of the above products lasts me six months exactly. I only wash my hair 2-3 times a week because my scalp is dry as is my hair. Some people might find that hard (my sister has to wash it every day, but it looks awful - I think it's more psychological - i.e. North American cleanliness standards) But, my hairdresser said 2x a week is plenty, and maybe 3 in the summer. Hope this helps!