diff --git a/machine_learning/pipeline.py b/machine_learning/pipeline.py
index cc10848..c328423 100644
--- a/machine_learning/pipeline.py
+++ b/machine_learning/pipeline.py
@@ -34,6 +34,7 @@ class SensorFeatures:
         self.df_calls = pd.DataFrame()
         self.df_sms = pd.DataFrame()
         self.df_calls_sms = pd.DataFrame()
+        print("SensorFeatures initialized.")
 
     def set_sensor_data(self):
         if "proximity" in self.data_types:
@@ -124,6 +125,7 @@ class Labels:
         self.df_esm_clean = pd.DataFrame()
 
         self.df_esm_means = pd.DataFrame()
+        print("Labels initialized.")
 
     def set_labels(self):
         self.df_esm = esm.get_esm_data(self.participants_usernames)
@@ -198,10 +200,13 @@ class ModelValidation:
     def cross_validate(self):
         if self.model is None:
             raise TypeError(
-                "Please set self.model first, e.g. self.model = sklearn.linear_model.LinearRegression()"
+                "Please, specify a machine learning model first, by setting the .model attribute. "
+                "E.g. self.model = sklearn.linear_model.LinearRegression()"
             )
         if self.cv is None:
-            raise TypeError("Please use set_cv_method() first.")
+            raise TypeError(
+                "Please, specify a cross validation method first, by using set_cv_method() first."
+            )
         if self.X.isna().any().any() or self.y.isna().any().any():
             raise ValueError(
                 "NaNs were found in either X or y. Please, check your data before continuing."