The phrase "keep to" is usually used to describe someone sticking to a plan, rule or agreement. However, there are several other synonyms that can be used to convey the same meaning such as "adhere to," "comply with," "abide by," "adhere," "stick to," "follow," "honor," "respect," "maintain," and "uphold." All of these words display a sense of loyalty and dedication to a certain course of action. Using these synonyms can help to diversify your language and allow you to communicate more effectively. By using varied words, you can keep people engaged and interested in your conversation.