Pick one small goal. Here are some ideas, or choose your own:
Practice using a "z" sound on the ends of words.
- or -
Practice using American intonation when saying "how are you?" (see video)
Select a sound you have difficulty with. Practice common words with that sound.
Set a practice time. Make it work for your schedule. Perhaps for ten minutes every day as you drive to work, do the dishes, or when you're talking with a friend.
Set reminders for yourself. We can have the best intentions to practice, but when we get busy, we tend to forget to do what we had planned. Use your phone, calendar, or a sticky note to keep your speech practice in the forefront of your mind.
When you get a good habit for practice, you can build on it. You'll see the changes in your speech that come from consistent practice.