Nothing wrong with pressure washing or using a hose with an attachment.
As above any major electrics, wires, battery, alternator to be wrapped. I normally use cling film. Please do not use kitchen foil, as stupid this may seem I have known a hand full of people to try it and others recommending it. Almost all modern vehicle engines wont be affected if any components get wet, as of most don't have an under tray neither, but its always safe than sorry.
When rinsing be sure not to flood any components, rinse only using a fine mist. If using a pressure washer, stand far back not to apply to much pressure towards any delicate parts. If in any doubts clean using a damp cloth instead.