Been watching various FS content creators for a month or two, including yours! I decided to dip my toes into playing by grabbing FS19 since 25 is coming. Just to be less expensive. It's been fun!
GPS, follow-me, and Course play mods are always a good idea when first starting out as a new player. Get used to the mechanics of the game first, then worry about making straight lines on your own.
-No Man's Land is probably the best starter map to get to know the game on. Huge mostly flat land with cheap squares of land you can buy in a satisfyingly beautiful grid pattern. -Color Configurator is the coloring mod he was talking about, also an awesome must have. -Easy Development Controls is the last MUST have mod. It gives you the power to change almost anything in your game. More money, flight, super strength, spawn bales, free refill on fuel or seeds or whatever. -Snap Build is probably my favorite mod. As a person with massive OCD this one helps me line all my buildings up nice and neatly in a row. -Paint And Terraform Anywhere is my last recommendation. It lets you paint the ground anywhere, whether or not you own the land, for free. You can also deform the land for free too.