Steps for Wardrobe Challenge:

1. Check the WHOLE grid. Look for a certain colour that has the most groups already. So don't just pick one standard colour every time. It really depends on how the grid is set up and which colour is most efficient to work with at first.
2. Make groups of that color, but don't click on them yet! Just scan from the left top to the right bottom and check if there is a single one without a neighbor.
3. Is there a single one? Try to give the poor thing a neighbor.
4. If you are done and see that every one has a neighbor, you can start making them all disappear. Start with groups that are at the top!
5. Go to the next colour that already has the most groups. If you're lucky you won't have to make any changes before removing them!
6. Eventually you will be left with one color and you're done!

NOTE: always try to think it through. Is it a wise choice you're making? Don't go too fast!
NOTE: I prefer to play it on my phone. If you lost, you can just refresh easily and you're back at it real fast. Just try it again!