Before your submit your articles to the article directories, be sure to read each directory’s Terms of Service and make sure you comply with them.
Also, be aware that almost all article directories do not allow affiliate links on the body of the article. And some article directories do not all affiliate links in the resource box.
Keep your articles to between 400 to 500 words for better readibility. If you have a long article series, break your article into smaller articles and name them Part 1, Part2 etc.
Here are some article directory sites you can submit your articles for FREE: