i've been reducing both the height and width of my privet in the back yard (was about 18ft long and about 11 ft high and about 5 ft wide) i'd recommend a pruning saw as well as loppers and shears, as some of the stems in my hedge were way too big for the loppers to get through and too tangled and crowded to use the bow saw effectivley.
you will make a massive amount of waste, so it's worth thinking about how you're going to dispose of it... i contemplated hiring a chipper and making my own chippings to use as a mulch somewhere else in the garden but in the end i decided to chop and stack the larger pieces for use in the woodburner in our camper van and bagged up the twiggy, leafy bits for the council to collect.
there was no way i was going to get it done in one go, so i divided it up into seperate jobs: tackle a 6 foot stretch at a time, do the width one weekend and the height the weekend after etc.... othewerwise i knew i' was going to put too much strain on my dodgy shoulders and lower back, as well as have a mountain of waste to deal with in one go. (once you get to 10 bags or over it stops being fun and you stuggle to find somewhere to stack them until recycling day!)
it's only a big job if you try and get the whole thing done in one go, divide the job into managable sections and it's not so daunting.