The best thing a musician does when recording is to make use of a good demo. A demo of the songs they have is useful when trying to attract more audiences to listen to their music. But if they release this as a selling album in itself, it may not sell as much and it might not be as clear, given the quality of production. It is best that you leave the production of your audio through a music producer.
A post processing engineer would also be your music producer since he or she has the expertise to know what sounds good for your band and how it should sound on the record. An album recording is an emulation of a band’s performance, which is why it is important to make sure the quality of the album is coherent with the band’s style and feel.
As a musician, focusing on these details while improving your craft could take some time with trial and error as there is no sure-shot way to making your music sound “properly” as it should. A music producer had worked their careers recording bands and going through trial and error to ensure they give the best quality for the bands concerned.
Remember to leave the job of directing the sound and quality of your album to a music producer, but prior to this, make sure that you find a viable music producer in the first place. Different music producers have different recording and mixing styles. Find the one that would most benefit your band’s sound in your album.