How to set multiple values inside an if else statement?

If you have more than one statement in a if condition, you must use the BEGIN ... END block to encapsulate them.

IF ((SELECT COUNT(*) FROM table WHERE table.Date > '2016-03-20') > 10)
BEGIN
 SET @test1 = 'test1'
 SET @test2 = 'test2' 
END
ELSE
BEGIN
 SET @test1 = 'testelse'
 SET @test2 = 'testelse'
END