How to advance in Duolingo put simply...
It is very simple.
Numero Uno: You need to make sure you use the WEBSITE on computer and not just the APP. You must be doing the website now if you are reading this.
Numero Dos: You have to not be afraid of asking questions even if you think they are stupid.
Numero Tres: Asking the questions and having the mistakes corrected in the discussions make you understand on a deeper level because you are not just being told the correct sentence (like in the app or a test) You are being told why the word or sentence is the way it is. If after being told those reasons you have further questions to that answer, those are answered also.
Numero Cuatro: Make the time. Doing all the above with your time helps you to advance on a deeper understanding. Instead of spending that same time getting answers wrong and wrong again until right and never understanding why that end answer is right, you get there so much quicker here & on top of that you leave with a better knowledge than just figuring it out through the app/test.
HOPE THIS HELPS SOMEONE BECAUSE ITS HELPED ME.