The word lose (as in "She will lose her sanity if she continues on her current path.") spelled like this: l-o-o-s-e, and losing (as in "She's losing her temper over a trivial matter.") spelled like this: l-o-o-s-i-n-g.
And then there are many instances of mixing different tenses in the same paragraph or sentence. For example: "She grabbed the burger and eats it." Either write "She grabbed the burger and ate it," or "She grabs the burger and eats it." Pick a tense and stick with it.
A dictionary and thesaurus are some of the most potent tools in anyone's writing toolbox. A writing workshop (an ultimately expensive undertaking) isn't there to teach spelling and grammar; by the time a person thinks of shelling out the bucks to join one, that person should have a good grasp of the basics.
Another good investment: a copy of Strunk and White's Elements of Style.
My own writing may not be perfect, but I make a serious effort to consult a dictionary whenever I write.