Cleaning aluminum soffit isn't a hard thing to do. Here are a few materials that you will need, along with some quick steps that can help you through the process.
Step 1 - Prepare
Begin with a ladder to reach the aluminum soffit. Use the hose to spray the soffit and get the entire surface wet so that you can clean.
Step 2 - Clean
Now that the soffit is wet, you can use the cleaning pad to wipe down the aluminum using an aluminum cleaner. You can look into homemade cleaners or opt to buy one. Wipe the soffit with the cleaner, using a soft-bristled brush for areas that need to be scrubbed more. Allow any spots to soak that need it.
Step 3 - Rinse
Once you are finished cleaning, you can rinse off the soap with the hose. Allow the soffit to dry and check once it has to see if anything needs to be cleaned again. If so, repeat steps. Once you are finished and everything has dried, you may want to look into the coating or sealing the aluminum soffit. Depending on the type of climate you live in as well as how old the aluminum is, it may be smart to protect it.