The "right" way to do stored procedure parameter validation

I have a stored procedure that does some parameter validation and should fail and stop execution if the parameter is not valid.

My first approach for error checking looked like this:

create proc spBaz
(
  @fooInt int = 0,
  @fooString varchar(10) = null,
  @barInt int = 0,
  @barString varchar(10) = null
)
as
begin
  if (@fooInt = 0 and (@fooString is null or @fooString = ''))
    raiserror('invalid parameter: foo', 18, 0)

  if (@barInt = 0 and (@barString is null or @barString = ''))
    raiserror('invalid parameter: bar', 18, 0)

  print 'validation succeeded'
  -- do some work
end

This didn't do the trick since severity 18 doesn't stop the execution and 'validation succeeded' is printed together with the error messages.

I know I could simply add a return after every raiserror but this looks kind of ugly to me:

  if (@fooInt = 0 and (@fooString is null or @fooString = ''))
  begin
    raiserror('invalid parameter: foo', 18, 0)
    return
  end

  ...

  print 'validation succeeded'
  -- do some work

Since errors with severity 11 and higher are caught within a try/catch block another approach I tested was to encapsulate my error checking inside such a try/catch block. The problem was that the error was swallowed and not sent to the client at all. So I did some research and found a way to rethrow the error:

  begin try
    if (@fooInt = 0 and (@fooString is null or @fooString = ''))
      raiserror('invalid parameter: foo', 18, 0)

    ...
  end try
  begin catch
    exec usp_RethrowError
    return
  end catch

  print 'validation succeeded'
  -- do some work

I'm still not happy with this approach so I'm asking you:

How does your parameter validation look like? Is there some kind of "best practice" to do this kind of