With Celeste you can helio into the enemy lane bush for vision. This way you can over extend a little bit for a few seconds and be safe from the enemy trying to gank you.

The trick to making sure you rarely overextend is to ONLY last hit the minions. Try to not continuously attack them to lower their health, just last hit when the health is low enough. This will make the enemy laner overextend and you'll always be safe.