• I (often) take a nap after lunch. (repeated action; habit in the present)
• She teaches Italian. (permanent state or occupation in the present)
• Spring follows winter. (general truth)
• The coach leaves London at 10 am and arrives in Manchester at 2 pm. (future timetable actions)
• Before the car blows up, the actor jumps out of it. (for narrating facts, movies, or historical events)

Present Continuous

• Anna is making a cake. (now, at the moment of speaking)
• Bob is learning to drive these days. (temporary action)
• She's always criticising other people. (Using "always", "repeatedly", etc for an unpleasant or bothersome action)
• Mike is taking an exam tomorrow morning. (planned action in the near future)

Simple Past

First of all, you must be familiar with irregular verbs. Look at your grammar book and learn them. There is no other way but just memorising them.

• She broke another glass yesterday. (action that happened in the past in a specific time)
• She opened the jar, poured the tomato juice and then added some water. (actions in the past one after the other)
• When I lived alone I always ate out. (with adverbs of frequency such as "always", "never", "often", "rarely", for a past habit)

Past continuous

• I was feeding the cat at 8 pm. (action with a duration at a specific time in the past)
• Mark was drinking his coffee while Susan was feeding the cat. (two or more actions happening at the same time in the past)
• She was feeding the cat when she heard the noise. (a continuous action interrupted by another action)
• I was always falling down when I was a little. (for unpleasant or bothersome actions that used to happen repeatedly in the past)

Used to - would