Graveyard Keeper

Collect 1000/3000 Green points

Tech Points are your skill-purchasing currency. They come in 3 different color flavors, Red, Green, and Blue.
Green tech points are earned from doing anything nature-related, or studying any nature-related items at the study desk.

This means things like chopping trees, harvesting crops, berries, apples, and flowers, and crafting food items. Some of those activities (such as chopping trees) will also award other tech points as well.

In addition to those physical and crafting activities, you’ll also find you can easily earn green tech points by studying items. When you hover over an item in your inventory or storage, unstudied items will show colored point icons. Any items that show Green tech point icons can be studied for an easy green point payout.

Earning these achievements for the Green tech points (1000 and 3000 points collected) is pretty easy and you shouldn’t have to worry about completing them. It’ll come fairly naturally over your gameplay (ESPECIALLY if you are striving to complete the game’s many other achievements - there’s a LOT to do in this game). After the red point achievements, these will quickly follow.

If you want this desperately quick you can dig up clay from the hole just south of your graveyard.
The clay pit offers endless supplies and for every piece of clay you dig up you get one green point.

You will just need to repair your shovel every now and again at the grindstone when it breaks.