[Kasis]

Well man, there are some nice techniques how to improve spellings. For example you split the words and see how are they build up. But really, I would suggest you to write it on note and place words you are struggling with in front of you, so you can look at it when you need it. Bad way is to google spellings because it makes you not to pay attention that much at it.
But getting to a point you are asking about, well, its hard slow study. From one way its just like your main language, you start with 'introduction' then follows the 'main story' you are about and then follows the 'ending'. So basically, that splits in three paragraphs. Typing fast what you are thinking makes one sentence a thought. To write decent article what you are about it takes rereading it few times and editing. That is the practise you need to do even though its slow and can be frustrating.
I would really suggest you to read books in English and see how whole story is build up and split. Even I have struggle as English is my third language and I can't perform good correct spelling most of the time. Most of the time I take basics from my main language to write something, like commas. But there is rules in every language, how it should be and there are cases of must. So man, just take it easy and pay attention.