My first advice to you is get ReSharper. It will tell you when there is a problem of possible null values, and when there is no need to check for them, and with the click of a mouse will add checking. Having said that...
You don't usually have to check for null strings and integers, unless you are receiving information from some legacy source.
Strings can be checked with string.IsNullOrEmpty()...
If you still decide that you want to check each and every parameter, you can either use the Command design pattern, and reflection, but your code will be unnecessarily clunky, or use the following and call it for each method:
private myType myMethod(string param1, int param2, byte[] param3)
{
CheckParameters("myMethod", {param1, param2, param3});
// rest of code...
And in your utility class put this:
///<summary>Validates method parameters</summary>
///... rest of documentation
public void CheckParameters(string methodName, List<Object> parameterValues)
{
if ( string.IsNullOrEmpty(methodName) )
throw new ArgumentException("Fire the programmer! Missing method name", "methodName"));
Type t = typeof(MyClass);
MethodInfo method = t.GetMethod(methodName);
if ( method == null )
throw new ArgumentException("Fire the programmer! Wrong method name", "methodName"));
List<ParameterInfo> params = method.GetParameters();
if ( params == null || params.Count != parameterValues.Count )
throw new ArgumentException("Fire the programmer! Wrong list of parameters. Should have " + params.Count + " parameters", "parameterValues"));
for (int i = 0; i < params.Count; i++ )
{
ParamInfo param = params[i];
if ( param.Type != typeof(parameterValues[i]) )
throw new ArgumentException("Fire the programmer! Wrong order of parameters. Error in param " + param.Name, "parameterValues"));
if ( parameterValues[i] == null )
throw new ArgumentException(param.Name + " cannot be null");
}
} // enjoy