When you say speaking, I'm guessing that you're referring to conversational skills (which also includes listening and comprehension) rather than public speaking

When you say speaking, I'm guessing that you're referring to conversational skills (which also includes listening and comprehension) rather than public speaking, which is often a problem even for native speakers. Assuming that, I think the most important thing is total immersion. You'll need to spend a lot of time having conversations in English, preferably with native speakers. Depending on your circumstances that advice may or may not be easy to follow. For example if you're not very social or have family you converse with in your first language those can be obstacles. The other thing to be aware of is that sometimes people have developed habits of speech or pronunciation that make their speech difficult to understand (or just sound strange) and they aren't aware of those habits. So you should also seek out some friends who are native English speakers and ask them to honestly evaluate your pronunciation. I'm a native English speaker and that is how I learned to speak French at an acceptable level, after a number of years of living in France.