Reading Urology : Urinary infections

You should aim to drink at least three litres of fluid each day, enough to produce a urine output of two litres a day. Any fluid is good.
You must make sure that you empty your bladder completely every time you pass urine. To check that this is happening you should stand up when you think you have finished and then sit down again to see whether you can pass more urine.
You must empty your bladder last thing at night before going to bed.
You must empty your bladder before and after intercourse.
You should drink a glass of water before going to bed and in the middle of the night if you wake up.
You must avoid becoming constipated.

These are the most important measures. There are other things which may be important in some people and which you should pay attention to as well:

Avoid bubble baths, highly scented soaps and vaginal deodorants. It may also be worthwhile changing over to tea tree oil soap, which is thought to reduce the number of infections.
Cranberry juice has been shown to decrease the incidence of infections. Cranberry Juice Tablets are available and an excellent way of reducing infections.
Live yoghurts may help and do improve some people's symptoms.
Do not wear tight trousers. Skirts are always better and you should try to wear stockings and not tights.
You should wear cotton underpants and wash these in soap flakes or non-biological detergents, not biological washing powders.
When you have had your bowels open it is preferable to wash your bottom rather than just use toilet paper but in either event you should always clean from the front towards the back.