Information wins games
The minimap tells you where enemies were seen, which lanes are pushing, and where your team can safely play.
Build a repeatable habit
Glance at the minimap after each last hit or spell cast when it is safe to do so. Notice missing enemy heroes before moving beyond the river.
Ask three questions
Which enemies are visible?
Which objective can my team realistically take?
Where can I retreat if enemies arrive?
Practice
Review one death from your next match. Pause ten seconds before it and look for information you could have used.