Dropdowns vs. Radios

It's really important to understand the importance of input field types. For example, when it comes to long boring forms, radio inputs become more effective than dropdowns with fewer number of options. As the list increases, to avoid reading through all the options, the latter must be used along with search field.
Such small things that we miss out while developing forms do effect the efficiency of users. Came across these while redesigning few forms for Aasaanjobs.
Comments and suggestions are most welcomed!