Is it acceptable nowadays to use both types of spelling in writing?
I have a tendency to mix up American and British English. This is because most of the South Asians have learned English in two ways simultaneously. 50% from academic books which are mainly of British Standard, and 50% from watching Hollywood movies/subtitles which are most times of American Standard. Therefore, it is almost a common phenomenon to find writings of students that have both types of spelling, and most of the teachers do not mind it at all.
So far, I can correct myself on using "o" vs "ou" based spellings. Although, it seems there are plenty more types of differences that exist between these two standards. And to fix this problem seems to be a mountainous task.