Hair grows from follicles, as new hair cells are made old ones are pushed out to the surface of the skin where they harden and die creating hair, so as hair is dead hair treatments effect on growth and hair quality are limited.
Trim and 'dust' - you can do this at home as long as you have a sharp pair of hair scissors, trimming is taking a bit of the end, where as 'dusting' is where you trim individual hairs as you see them, when they have split ends. It's an old wives tale that cutting your hair makes it grow faster, your body can't tell when your hair has been cut, but cutting your hair will help hair grow longer. What I mean is that split ends travel up the shaft of the hair, damage further up the hair means the hair will break, and the hair breaks it can't grow any longer. This does NOT mean to trim all the time, this would mean for whatever your hair grows you are cutting it so it would take forever to grow, just trim it when it is needed and 'dust' in the mean time to get rid of the damaged ends without taking length from your hair as a whole as trimming would.
Massage your head, it promotes circulation to promote growth, get into the habit of massaging as often as you can, before washing your hair and also massage during washing your hair. I like to massage a few drops of rosemary essential oil into my scalp before washing my hair, as rosemary is believed to stimulate hair growth. Another suggestion is to massage monistat into your scalp, yes it's a yeast infection cream, but it contains some of the same chemicals as rogaine so stimulates hair growth only without costing the earth.
Stop using shampoo, it doesn't mean not washing as there are plenty of other ways to wash your hair, it's one of the best things you can do for your hair as shampoo strips hair of natural oils that it needs to stay strong and healthy so makes hair damaged, frizzy and generally not great looking - it also means your scalp overproduces oil so your hair actually get more greasy using shampoo. There are different ways to wash hair without shampoo, I recommend conditioner-only/curly girl method, for this you simply use conditioner to wash hair with as this has enough detergent to cleanse but won't strip hair of natural oils as shampoo would. Seriously, don't be scared to try it as you're guaranteed better hair, your hair will be much healthier, stronger, shiny, easier to manage, it won't get greasy as fast, and healthier hair will grow better. You can read about curly girl method here http://motowngirl.com/no_shampoo.php and read more about shampoo damage here http://babyslime.livejournal.com/174054.html If not willing to ditch the shampoo at least try cutting down on how often you shampoo, go for shampoo's without sodium laureth sulfate (SLS), it's a common ingredient that is very drying, look at shampoo brands like Neal's Yard, or Lush which does still contain SLS but fewer other harmful ingredients.
It also helps to avoid chemicals as much as possible, even products that claim to improve hairs condition can be damaging - for example many split-end or smoothing treatments contain silicone, which works by coating the hair so make it look healthier, but in the long-term it causes far more damage than good to the health of your hair. Look into natural brands, silicone-free and SLS-free products, also consider home treatments like homemade hair masks. If you use dies then these will cause a lot of damage, so consider switching to henna as this will change hair colour while also being a fantastic conditioning treatment, the best place for henna is http://www.hennaforhair.com
Avoid hair dryers as overheating can damage your hair and never rub with a towel as it will damage the hair cuticles, instead leave to dry naturally or if you do use a hairdryer use protecting sprays and choose a dryer with lighter or cooler settings – use until your hairs 90% dry, no more. Also try using a wooden comb to brush then a hair brush with natural bristles as these are much gentler on your hair and can improve shine, another tip is to use a satin or silk pillow as this prevents hair snagging as it can on other materials.
Things such as stress or bad diet can seriously effect your hair, I saw the huge effect diet has on hair when one of my friends sadly became anorexic, the effects started showing alarmingly fast, her hair became so brittle it would literally fall apart in her hands. Don't underestimate the importance of diet, don't follow fad diets or yo-yo diet, instead keep up a good healthy diet at all times. Particularly helpful foods are oily fish like sardines, oats, nuts, seeds, guavas, papayas, and of course lots of water, using a good multivitamin will help (hair & nail vitamins aren't necessary) and also I'd recommend flax seed oil in capsule form.