If you have access to a computer, why not just use a spellchecker :)
I print my stuff on actual paper and do a manual proof read when I think I’m done. I’m constantly surprised by how many spelling mistakes I still find during final proof reading that Word isn’t underlying with red squigglies.
Spellchecking isn't universal, and I've frequently found myself typing completely different words than I had intended, which are not misspellings. That would be picked up pretty quickly.
Case in point, it probably wouldn't have picked up this submission's title if 'phased' had been written instead as I commonly see these days.
I do, but I'm not going to rely completely on one.
It's easy to autocorrect something to the wrong word. Or write a sentence that passes a grammar checker but is still sketchy.
This is also my favorite. It also works pretty well for punctuation and general flow, I find.