I strongly reccomend:

1) for the maps: an Expanding File Folder
2) for all the pieces: a couple storage boxes I found 2 of these at goodwill for a couple bucks, but they're $3.19 at amazon, so hardly breaking the bank either.
3) Gloomhaven Helper <--- this will save you so much time in setup, it replaces all of the monster decks with 1 simple tool, for web/pc/android