Create a single instance of your application To allow only once instance of an application, use mutex  found in the System.Threading.Mutex namespace References https://msdn.microsoft.com/en-us/library/system.threading.mutex
Quick Tip : Implementations of cryptographic hash algorithms To generate an MD5 hash of a file you can use HashAlgorithm in .Net References : https://msdn.microsoft.com/en-us/library/system.security.cryptography.hashalgorithm(v=vs.110).aspx https://en.wikipedia.org/wiki/Cryptographic_hash_function
Quick Tip : Display the file version of your application in C# To be able to display the version of your application can be very helpful, especially if you do support on the product and you need to find out what version the user is running. Version numbers typically display as major number.minor number.build number.private ...
Compress folders in C# Compressing files and folders can easily be done by using system.io.compression
Compress files and folders using sevenzipsharp and 7-Zip in C# Compressing files using 7-Zip and seven zip sharp (http://sevenzipsharp.codeplex.com/) is really easy. To get started you would need the 7-Zip DLL (www.7-zip.org/download.html)
Log Data to a File You can easily write a collection of data to a log file by using System.IO.File.WriteAllLines method. The File.WriteAllLines method take two parameters, the output file and a collection of string entries. The method writes each entry on a new line.