Start by finding somewhere quiet and reading the document out loud yourself, you will catch so many issues this way (though you still risk your mind filling in blanks or missing your common errors). Ideally this will be to someone else, they can help you find issues or question where things aren't clear - but even alone you will get value if you take your time.
As others have said, I then use a 'read aloud' tool such as the one in review in Word, sadly PowerPoint doesn't have the same tool.
Do a search for things you know get missed - one for us is double spaces and using a hyphen or minus sign - in place of a long dash —
Search for all common abbreviations and replace with the full word
Make sure there is a single date format throughout the deck
Check bolding, alignment and fonts
...
The list could go one, but I find that just concentrating on one thing at a time really helps - don't try to look at a whole page and find all the issues. And don't stop - make sure you keep reviewing as the final edits go in, the worst thing is someone pasting an update in from an email and messing with fonts/alignment etc. Just before you submit.
And give yourself time - maybe 20 percent of my time is spent writing a deck, 80 percent is spent editing, refining, validating and getting levels or approval.
The point of a great paper or deck is to be respectful of your audiences time. Make sure that you don't offer them the chance to get distracted by something - you want to keep their focus on delivering the answer you are looking for.
In the past I've seen so many meetings thrown as people get hung up on errors in the materials which eats into their confidence with the presenters - wasting time and focus.