Tick anything you already have, in any order. Quests unlock once this is done.
Borrow one first if you can. A cheap guitar set up well beats a dear one that is not, and the tuner matters because an out of tune guitar teaches your ear wrong.
2 things left above. Quests are real things you go and do, so they only make sense once you have what you need.
First one waiting: Play G, C, D and Em with every string ringing