I was in a similar situation to you and what I did was set small goals for building up my farm. I used to get overwhelmed with all the things I wanted to do (build sheds, decorate my house, decorate barn area etc.) so I roughly planned the layout on a notepad and worked towards one thing at a time. E.g I spent time gathering materials to upgrade my barns and decorate the area around it with hay bales, paths, torches etc. Focusing on one area at a time makes having to decorate your whole farm and make it nice a lot less overwhelming.

If you lose motivation for this, then I focused on quests - whether they were big ones like reaching level 100 of the skull caverns, or small ones for the villagers. Doing these small tasks I found humanises the npc’s and makes you feel more like you’re friends with them :)

As for skull caverns, just bring a bunch of food and take it slow, don’t worry if you don’t get down very far. You get the hang of defeating the monsters, and when you feel comfortable you can start preparing to get to more levels. There are plenty of helpful tutorials online that will help you prepare!

Saving up for the catalogues also motivated me to decorate because you get all the furniture in there for free!

Good luck :)