You really don't have to strain at all! There is almost no benefit.
But if you want to, buy two paint strainers that fit 5 gallon buckets (in the paint section of a hardware store.)
I have only strained once. I think I will only do it when I brew beers with tons of hops. I would rather have the hops stay out of the beer once they have done their duty. The bottom layer of trub can really take up a lot of space if you add 4+ ounces of hops. All of that trub will take up space, and it will hold beer. I literally lost a gallon of beer when I racked to primary, to seconday, to bottling bucket...