Although you can play any of the four Ring segments in any order you like, you can avoid some continuity issues if you tackle them in this sequence: "Alberich," "Loge," "Siegmund," and "Brünnhilde."
Check synopses
Check out synopses of the four operas that make up the Ring Cycle--The Rhine Gold, The Valkyries, Siegfried, and Twilight of the Gods--to get a better idea of what's going on in Ring. (Unfortunately, you'll also discover how much has been left out of the game.)
Inventory Items
If the cursor changes to indicate that an item in the game screen can be manipulated with an inventory item, try using every item you have in your inventory, even if it doesn't make sense. After all, this game doesn't make a lot of sense, either.
Scan Location
Scan each location carefully for areas you can explore, while keeping a close eye on the cursor to see if it changes to the Movement icon. Sometimes the "hot spot" indicating a new location is quite small.
Avoid continuity issues...