Dunno if you've heard of the Swedish system that consists of counting points.
Basically, all hours between 06:00 and 22:00 will give you 6 points per hour.
Between 22:00 and 06:00 you will get 8 points per hour. Every landing costs you 5 points. You are allowed to accept a schedule of max 90 points per day with landing points included. If you fly this day and for any unforseen event, you need to exceed 90 points (weather, diversion etc) you may go up to 108 points.
For any given 7 day period, you are to have no more than 270 points planned excluding landing points. That kind of takes care of the long term fatigue.
As for rest, you rest down your points in the same way you accumulated them ie. 8 points between 22:00 and 06:00 and so on.
It's a reasonably complicated system, but works fairly well. Some argue thought that it's not the amount of landings that should count but the number of approaches... A day with poor weather and many minima go arounds will be a lot mor fatiguing than a clear day with no go arounds.
But even though you are within your legal points limit, you can still FEEL fatigued. Everyone is different and sometimes you sleep poorly or are under a lot of stress at home etc. In that case the only protection is your own say and to let those in charge know that you are not fit to fly.
Regarding managing fatigue on the line it is all about using all the available help all the time. Don't try to proove things by doing things "your" way. It's not about doing things as if you're about to pass a CAA check. If you fly an NDB approach, use guidance from the FMS if available etc, ask for vectors rather than doing full procedures and so on. Make life simple. But not too simple so that it becomes booring because that tends to bring on another type of fatigue.
When it comes to safety, you need to be able to recognise when you are fatigued. If you don't recognise it in time, the first thing that comes along is complacency. You find yourelf being very comfortable in just not doing stuff you normally should do and that's when the !!!! hits the fan. For me I'm especially cautious early mornings and around 15-16:00 after having a meal. That's when I try to really adhere to SOP's and do things by the book. That way I'm certain I wont miss vital items and so on.
It's a big subject and what's interesting is that just being a little bit too tired can result in so many more problems... That's my five pennies worth.
/LnS