There are multiple links in the article referencing what you seek. > There seems to be a vauge grey line between being properly assertive and being selfish or

There are multiple links in the article referencing what you seek. > There seems to be a vauge grey line between being properly assertive and being selfish or being a jerk. Do you know someone who is assertive yet polite? If so, mimic them for a while. Like many behaviors, it can simply be a matter of practicing.