Starting is the hard bit. You need to have an idea of what type of layout you want. Things like tight curves can be a bugbear later on, so go for the widest radius possible. Control systems - DC or DCC should be considered - once you've made up your mind it's very hard to change. The basics, like track, control systems, make initial setup a bit expensive, but it gets easier after that. If you've got most of this from your father's system, then have a go. An old mentor told me: "There's very little you do that can't be undone", so don't be frightened to have a go; it can generally be fixed if you make a mistake.