If you want to start laying down ideas and eventually producing full tracks it helps to have a good computer with some sort of Digital audio workstation (commonly abbreviated as DAW) such as Pro Tools, Logic Pro, Ableton Live, GarageBand, etc where you will be recording or adding your music and beats. Besides that, if you play an instrument (such as Guitar, Bass, Keyboard, Vocals, etc) you could buy an audio interface that will help the computer process the audio and make it easier for you to plug in your instruments to the computer to record with your DAW. The Focusrite scarlett series is on the more affordable side and respond very well, on the more expensive side you can fide Apogee and the Apollo interfaces from Universal Audio. Headphones or speakers with a fairly even response should be good too. Besides the necessary cables, instrument, and necessary ram and hard drive space with these things you should be good to go to start producing plenty of music.
This website has some good additional comments and recommendations: https://ehomerecordingstudio.com/home-recording-studio-essentials/
Joan recommends the following next steps:
- Find or upgrade your machine to have plenty of ram (about 16GB if possible) and space (more than 100GB should be fine to start) since this gets used up a lot the more layers you add.
- Decide which DAW to learn about and which is most relevant to you. (I personally use Pro Tools for studio sessions with other musicians, and Logic Pro a lot more for mockups and laying down ideas)
- Decide if you need, want, and can acquire an audio interface. I'm a bassist, composer, producer and I use an Apogee Duet as my primary recording interface when I'm at home or traveling but I also have a Focusrite Scarlett 2i4 just in case anything happens to my Duet and I don't want that to hinder my ability to finish a project.
- Find out which headphones or speakers are the recommended ones for a home studio. There are many opinions about this. I've used both KRK and Yamaha HS series. The headphones have the added benefit of making it easy to move around if you travel often. Most people eventually buy both.
- Read all the manuals and most importantly: HAVE FUN!