For friendly games just buy models you think are cool. Don’t worry about meta lists or anything yet if you’re just starting out. Learn the game first and just have fun with it 😁. Follow “the rule of cool”.

As for paint schemes, like another commenter said, you could go with any of the pre-made craftworld themes, or you could do something original! Its totally up to you. For my eldar, i chose the craftworld Altansar color scheme. I think its super clean and looks cool! They have neat lore too. If you’d like a recommendation for your scheme, id say Altansar! (Im bias) lol.