you would use a comma after.
example:
dear Mrs.Smith,
I was pleased to meet you.
sincerly, NK
 
        
             
        
        
        
There are many research processes that can be followed according to the field of the research. However, we can usually think of a 5-step research process for general matters:
- Locating/defining the theme/problem or issue;
- Designing the project;
- Collecting data;
- Interpreting research data;
- Reporting research findings.
If following these steps, "creating notes of information he found so far"  would belong to step 3: collecting data. Those notes must be neat and organized so that they will serve for consultation and even citation in the future. The analysis of the information noted is also important for the development of the research.
 
        
                    
             
        
        
        
Wallstreet crashed in 1929, bankrupting those who held stocks in buisnesses, and those buisnesses suffered. Banks failed and people were unemployed 
The dustbowl followed after,  thus contining the depression on longer. Dust storms bothered crops, and made living conditions harder. 
        
                    
             
        
        
        
A young boy named ...
Once Upon a Time, there was a boy named ...
The boy learned a valuable lesson today ...
The little boy wandered through the woods...
Not sure what you were looking for buy I did my best. I hope this helps. 
        
             
        
        
        
Talking and understanding the others point as well