The hardest skills are surely flirting and idioms. I bought these and i had SO much problems! They are nice, but almost everything i got wrong. Anyone else too? (Not that they are horrible skills, they are just so hard!) I love Duo and French is a good language but the hardest skills are flirting and idioms to me. What do you think that is the hardest skill? Idioms and Flirting too?
I don't know about flirting but idioms is supposed to be the hardest as they often don't translate literally. They are optional but I still find the inclusion and especially the placement of the idioms skill questionable in a tree aimed at beginners. I don't think any of the volunteer teams has plans to include either one on their trees.
Generally speaking, idioms and flirting are supposed to be post-completion skills. As for right now, since I'm not all that far in, I'm just floating along. But conjugations are still not great for me, as I'm not in a French class and I haven't found where a conjugation chart is on Duolingo.
Everything is so hard! My landscape-designer is a young woman whose husband is French, and after they returned to the US from visiting the husband's mother in France last summer, their then-5-year-old daughter asked "Can we just speak English now? My head hurts!" That's how I feel...after only 20 minutes on Duolingo, my head hurts!
Tough as it may be, it is not compulsory to do that at a beginner level. I did the skill too when I was a beginner, and found it tough. But I came back to it after I had progressed down the tree and found it easier. Then I bought the Flirting skill and it was very easy. I guess you shouldn't worry about it at your stage - these skills will be the least of your concerns when you start learning complex conjugations, different moods and tenses! The hardest for me are the PC units (passe composse). Those 2 bonus skill's placement in the tree is wrong actually - it should be further down.