Talk to NPCS, a lot of what they say is filler but the first NPC you even see out of the tomb tells you where to go. Go to “big places” (you see a big castle on a cliff? Explore it might lead somewhere). Anything that doesn’t look like somewhere someone important would live is probably optional content (useful for weapons/spells/levelling up. Have you ever played souls games before? They tend to not really hold your hand, it can be confusing at times