What should I consider before I upgrade my SQL Server memory?
There is not much to check if you have found out that SQL Server requires more memory.Is your OS on physical machine or Virtual if it is virtual adding memory would be easy.

You must know that SQL Server 2012 standrd edition supports maximum of 64G memory. After adding new memory you must change max server memory setting using sp_configure. Set max server memory to appropriate value. Leave enough memory for OS and SSIS, SSAS,SSRS if you are using these features.