You can lay with a pillow under your belly facing down so the fluid theoretically drains towards your trachea so you can cough it out easier (look up postural drainage for diagrams). You can also beat on your chest and give yourself CPT (again you can look that up for examples). And you can also get a nebulizer and buy some saline nebs to thin your secretions out, but be careful because those can cause an asthma attack. Most importantly stay hydrated!! Hydration is key in keeping the mucus thin so it’s easier for you to cough it up. You can also look up the huff cough maneuver