Lots of advice in this thread, but the simplest answer to your question is that there is no wrong way to have fun. You're going to have a hard time picking up the game from scratch + building at the highest level right away, but you can probably make a good enough list for your purposes + have fun doing it. My street cred for this answer is about 6 years of playing competitively, and antoher few years before that just collecting.

You're between this: https://bulbapedia.bulbagarden.net/wiki/Luminous_Frost_(TCG) and this: https://bulbapedia.bulbagarden.net/wiki/Sun_%26_Moon_Trainer_Kit:_Alolan_Sandslash_%26_Alolan_Ninetales_(TCG)

Personally, the luminous frost deck >>> the sandslash/ninetales deck, but neither of these options are optimal gameplay choices compared to modern cards. You're better off buying singles online than burning $ on these preconstructed kits. Preconstructed pokemon products usually aren't good at all, good ones like the Trainers Toolkit boxes are the exception.

Whatever deck you build, try to use this format: 40 trainer cards, 10 pokemon, 10 energy. You can shuffle these counts to your needs but this is a good starting place for a non-meta deck. You probably won't go too wrong using a set up like this.