* Always use qualified name when calling stored procedures. for example EXEC dbo.Your_Proc

This is very common mistake which cause an extra trip to procedure cache to get execution plan for execution. SQL Server compiles stored procedure on its first execution and store the execution plan in procedure cache to be reuse in subsequent call for same sproc. In order to get the execution plan it require qualified stored procedure name e.g. dbo.My_Proc (fully qualified name contain Server.Database.Owner.My_Proc). When owner name is not specified then initial cache lookup by object name fails as owner name was not specified. SQL Server then acquire exclusive compile lock on stored procedure and all the referenced objects including tables for recompilation. Next step SQL Server will resolve the object name to a objectID and before compilation it makes another trip to procedure cache by using object id that can result finding previous exection plan. But as you noticed this can cause blocking in certain situation where many SPIDs are calling same sproc frequently and while its is lock for compilation all the caller have to wait until sql server find the execution plan in cache or recompile the sproc.

So the rule of thumb is Always qualify your objects (sproc, tables, views, functions) with owner name.