A book is a longer term process, publication can take maybe even 2-3 years from submission with payment made in the form of royalties depending on contract.
A magazine article is a one off with a single payment with possible additional payment for added photos or illustrations.
The first step is to research your publisher. Find out what they want. Plan even before you start writing. With a novel, you an send in the first 3 chapters and a synopsis before finishing the rest.
With an article, you can send in a proposal. What is the article about, how many words, illustrations etc. Sell it before you write it. If submitting without doing this, remember lead times. It is no good sending in a Christmas article in November. These are written in April. All date related articles should be submitted at least 6 months before relevant date.
Check previous articles and always submit something different from anything recent. Look up really old issues and look for something on a subject they've published before, but needs updating due to changes in technology etc.
WORK at being a writer.