You can begin by tapping to the plus sign icon found on the bottom of the mobile app. Then, click the "Log Action" button to begin logging your activity. 

1. Add an Action Title or Subject: You can provide a concise title or subject that describes the activity. This could be anything from a formal meeting to an informal interaction like a meeting with a Client or 'Informal Chat.'

2. Add a Task Body with Specific Notes: The Task Body section is where you can add detailed notes about the activity. You can include specific information, such as "Dropped off cookies at client's office" or "Discuss project updates over coffee."

3. Log To: You can log the activity to a Contact, Lead, Account, or Opportunity. Search to assign the activity to the relevant record in Salesforce. 

Update Salesforce Task Type for Context: To provide more context about the activity, you can update the Task Type field. This field pulls directly from the field defined in Salesforce and helps categorize the activity, such as 'Client Visit' or 'Drop In.'