Calculate minimum gutter fall of 1 50 that is for 2mm of fall for each metre of gutter then put a nail at the lower end and fix a stringline between the nails and check fall with a spirit level.
Fitting internal gutter brackets.
Take the first length and clip it into the running outlet then into the facia board brackets.
Having fitted the gutter brackets it is time to fit the guttering.
If you live in an area that is prone to regular heavy snowfalls position fascia brackets so they are no more than 400mm apart.
Clip the two ends in and fix to the facia with a suitable screw.
Join the next length of gutter to the first with a union bracket.