Hollow Knight

• You can double-tap your map button to open the larger map.

• Listening to sounds can be a big help for finding secrets.

• If you're having trouble with an enemy, try jumping and slashing downward. This also refreshes jump abilities, and is a necessary skill by midgame.

• Don't worry too much about any Geo you lose by dying, you'll have plenty by the end and it's easy enough to grind for it if you really need to.

• You can't miss anything that counts towards 100% completion, but you can miss some enemy journals. If you're anywhere that seems ephemeral, make sure you get all available entries there.

• Your air mobility is much better than your land mobility at first. Whenever you're fighting something, either be in the air, or let it come to you.

• If you are going for 100%, the most obtuse charm can only be found
  when you have 15 or more Blue Masks
  .

• Experiment with different charms; very few of them are actually bad, some just don't suit certain playstyles. Some interact in interesting ways.

• You will want to use different charms when you're fighting bosses than when you're just exploring.

• The living have dreams too.

• You will lock yourself out of the first ending when you
  transform the complete two-part charm into something else
  , so if you want to see that ending, make sure to fight the final boss first. (You'll continue from outside the boss room when you reload.)