It's hard to read your own writing critically, but it's something you'll have to do. One way to make it easier is to read your work out loud.
This has two advantages.First, it slows you down. You can't skim over text as quickly when you have to speak the words, and this makes it easier to spot typos, repetition and other such mistakes.
Second, it transforms writing from a bunch of words on a page into actual sounds. Writing is, in essence, a form of idealised speech, and good writers know how to use the sound and rhythm of a sentence to get their message across.
That requires, of course, a high level of skill. The first step towards developing that skill is simply paying attention.