[nq:1]When coining words, how should I choose which of these four suffixes to use? ~Iain[/nq] What word? You can use any one of them, but that depends on the word you want to coin.
You can use the suffix "-hood" to refer to a period of time or a state: during his childhood (=when he was a child); parenthood (=the state of being a parent). Or to refer to the people who belong to a particular group: the priesthood (=all the people who are priests). You can use "-ship" to refer to: 1. a particular position or job: professorship, premiership; 2. the state