Use "at" when referring to a period of the day or exact time, as in "at 10 o'clock" or "at sunset." Use "in" for months, years, decades or longer periods of time, such as "in 1998" and "in spring" and "on" for days and dates, such as "on Tuesday" and "on July 4th." Some exceptions include the common expressions "in the morning, in the afternoon, in the evening" and "on Wednesday morning" for example, even though they refer to periods of the day.
Choose "in" to show the exact point an object or a person is located; for example, "Mum is in the kitchen." "Inside" indicates that a person or an object is contained somewhere, as in "My toys are inside that box." Use "at" before home, work, specific addresses or when talking about the general vicinity, as in "I'll meet you at the corner."
Use "since" to express duration, starting from a specific date or time, as in "I've known him since high school" or "We've lived in California since 1999." Choose "for" to focus on the duration of an action or situation rather than when it started; for example, say "I've known him for seven years" or "We've lived in California for 12 years."
Place "for" before a noun, pronoun or phrase to show that this is the target of your verb. For example, in the sentence "I'm asking for information," "for" shows that my goal, when asking, is information. Similarly, "He's looking for his keys" shows that his goal is to retrieve his keys.
Express movement with "to" or "toward." For example, say "I'm going to the cinema" or "The cat is moving toward the mice." However, certain words don't need a preposition at all, as in "He's going home" or "The dog went outside."
Learn by heart prepositions always attached to certain words, regardless of what follows in the sentence. Examples of such cases, which are part of formal English speech and not colloquialisms, include "approve of," "discriminate against," "familiar with" and "capable of."