Key for the map icons in game

Funny enough, I just completed this achievement recently. I can tell you what I avoided that made it easier for me. You may choose to do some of these and trade them out if that is easier for you.

So I skipped the following:

• I did not fight Grimm, nor Nightmare King Grimm (2%)
• I did not get the last mask fragment for light from carrying that white flower to that grave (1%)
• I did not hear the Seer's final words by getting 2400 Essence (1%)
• I did not fight the warrior Markoth (1%)
• I did not complete the trial of the fools (1%)
• I did not get the King Soul/Void heart charm because I didn't trust my platforming skills in the White Palace (1%)
• I did not get the Godtuner and therefore did not do any of the pantheons (5%)

I believe that is how I did it. Also, a pro tip if you don't mind cheesing it a bit: Don't be afraid to pause and quit to menu when you get to low health. You'll restart at your nearest bench with full health.

There is no reason to hold on to them until you have them all as you can't sell them in bulk. The game also doesn't give you any completion percentage or achievements based on collecting any or all relics.

On the contrary, relics are designed specifically to be sold. When given to Relic Seeker Lemm, he will tell the player snippets of lore about various pieces of the kingdom's history. If you want to experience all of the lore the game has to offer, you need to collect all of the relics and sell them.

The other advantage of relics over just giving the player a large pile of geo is that relics are not lost upon death. This means that collecting relics is a safe way to hold on to geo until you need it for a specific purpose such as the situation you have described. Now that you have a good place to sink your geo into, you should sell as many relics as you need to buy those items, and take this opportunity to learn more about the world of Hollow Knight.