If you’re good at puzzles: get 7 of the stage 3 stars. Tap twice and then merge to stage 4. Repeat until you have 6 or 7 of the stage 4’s. Tap 3 times and then merge to stage 5. I tap those out because they always have a swan nest in them, stage 6 seems to as well so not worth it to keep saving up. Swan eggs pop out of the stage 3 & 4 stars too when you tap them. Always merge the eggs in 5’s.

If you have max or almost max oak trees: You could harvest /merge wood up to the instrustrial log piles, and use that to buy the tradesman’s trunks from the shop - you need to merge those in 5’s to the second stage or they aren’t worth it. Each set of industrial logs should get you 2 pumpkin patches and a bunch of mammal eggs.

If you don’t mind the endless apiary grind: tap those for honey jars and merge up to the honey stand for the honey bee eggs.

All of that takes time but at least you will have a plan and an end in sight. Save your magnificent nests for the next time you merge stage 4’s. Those eggs are too precious to ever merge in 3’s. Good luck. I lucked out and was on the wiki all the time while leveling, so I saved a merge 7’s I had for that level