It's never too late to learn :P
A good first step might be brushing up on your english skills... you can not just write more convincing advertising material the more fluent you get, you also end up writing more professional-looking material. A lot of people can be really strict with typos and grammar errors and that can really hurt your first impression.
(I'm personally not a native english speaker either, and I still do some basic mistakes like mixing up 'was' and 'were', but I'm actively trying to improve all the time)