Hi, prepositions are difficult but unfortunately there are no short cuts, prepositions need to be studied and practised until you remember which is used where. Perhaps a good idea to practise is to write and post your work in "notebook"using different prepositions, by doing this, your work will be corrected and you will be able to see where you are making mistakes and hopefully learn by them.

Sorry to say this, but you simply have to sit down and learn them. No magic tricks here.

As the others said, you'll need to study each preposition. However, here is a quick overview: To - Indicates direction of movement (it also used to make the infinitive form). By - Describes 'how' something happens/happenned. It can also describe when something is physically beside something else. For - Describes 'why' something happens/happenned ie. it decribes the reason the verb is happenning. About - This is the hardest one for me to describe. If 'by' corresponds to 'how and 'for' corresponds to 'why', then it makes sense to me that 'about' corresponds to 'what' (sort of). I'll give a few examples below. Ex. "I'll walk by the beach to the shops to buy something for you." Here, 'to buy' is infinitive, 'by' means 'beside' and describes where the walking took place ('by the beach'), 'to the shops' is the direction, and 'for you' describes why I'm buying something ie. to give it to you ('to give' is infinitive and 'to you' is the direction of the giving). Ex. "I'll get there by driving. I'll drive by the lake." '...by driving' is how I'm going to get there. '...by the lake' indicates I will drive beside the lake. It may or may not mean I'll stop at the lake, depending on where the emphasis placed. Ex: "What I like about the ocean is..." "I don't know (anything) about maths/cars/engineering." "He always talks about tennis." 'About the ocean' specifies what 'what I like' specifically refers to. I hope you can figure out how 'about' is is used from these sentences. You're textbook probably has a much better explanation. All four have exceptions and all exist in phrasal verbs with different meanings than you'd expect. What I have written here hopefully will help you when trying to understand what someone has written, but if you want to use these four words I suggest that you find a more formal explanation than mine.