Easiest way to record a song at home?

So, does anybody know the easiest and the cheapest way to record a song professionally (with studio like quality) at home? Recording studios are pretty expensive! Right now, I simply plug in a mic to my Lenovo Z570 laptop, use Audacity and record in a closed room. Definitely the quality isn't good, so any suggestions?

Also should, I separately record vocals and the instruments and put them together?