This is a good time of year to get a new Mac as even Apple hardware is on sale. Jason Cipriani has a good step-by-step to set up a Mac for the first time.
For starters, the process can take several hours if you plan on transferring your data from another computer. Then there are aspects to consider such as FileVault and if you need it, or how you get information off of your old Mac or PC and onto the new one.
Always fun for experienced Mac users, easier for new Mac users who follow the steps.