As Oliver Pritchard explains, they’re easy to get wrong, but not hard to get right. So practise, practise and practise some more!
Spanish prepositions are quite easy and have some very basic rules. However, this is not the case for English prepositions. They are quite random, follow few rules and have many exceptions and irregularities. This means that you must be very careful when using them and spend time learning the correct usage.
Also, it’s useful to try to think with your heart rather than with your head: a lot of English language prepositions use ‘what feels right’ and not a rule. Of course the Spanish prepositions and English prepositions are sensible and function. Be careful with direct translations and think more about the idea.
There are also considerably more prepositions in English than in Spanish, for various reasons. This is important, because it is often the case that where Spanish uses one preposition, English uses three. This naturally leads to problems.
A note: some teachers will tell you that prepositions can never go at the end of a sentence. That’s bollocks. It’s all a strange idea invented by people seeking to impose a strict set of laws on a naturally chaotic language. A perfectly fine example might be “what are you talking about?”
Prepositions of place should be easy, and at the basic level they are. However, there are some problems even at low levels. A common error with Spanish speakers is that en is equal to two different ideas in English: in and on. In is usually used as the translation, but this leads to some very strange phrases such as ‘in the table’ or ‘in the bicycle’. Of course, context normally makes things obvious, but it can lead to serious confusion: ‘in the table’ means I will look for something in a drawer or box; ‘on the table’ means I will look on the top of the table.
Be careful with among and between. Among is almost always used for large numbers, but between is usually used for two things. ‘The Magdalena river is between Bogota and Medellin.’ ‘Juan is among the students.’ ‘I chose between Santa Fe and Millos.’ ‘Among the many sights of Bogota is Plaza Bolivar.’
Connected to prepositions of place are prepositions of direction, which explain how and where we move. Happily, these are fairly uncomplicated in English and quite similar to Spanish. To and from are the two most common prepositions, along with left, right, up, and down. But try to increase your range by using more advanced prepositions such as towards, away from, through, over etc. The more you practise your prepositions, the more natural you will be when using them, and the more you get used to using more of the prepositions, the fewer mistakes you will make by overusing them too.
Also, if you are writing reports or interpreting data in English, you need to be very careful with prepositions. Grew from and grew to are two very different things indeed. From highlights the starting point, and to highlights the finishing point. Obviously, mistaking these concepts creates problems.
Again, the English prepositions take multiple forms here. In Spanish a or en are generally used to mark basic time prepositions, but even at elementary levels of English you need to learn on, at and in. It’s helpful to think about size here: in for big things like weeks, months, and years; on for specific points, ‘on Wednesday’ etc; at is usually used for exceptions, for some reason ‘in the morning’, ‘in the afternoon’ but ‘at night’. At also refers to hours/minutes/seconds: ‘at 5 o’clock’.
Possibly one of the most fun areas of English, but one that creates many problems for students, is phrasal verbs. These always take the form of a verb with an adjective. In the same way that Spanish verbs change with the addition of se (ir/irse for example), so many English verbs change depending on the preposition. Again, these usually have some sort of meaning connected to the preposition. Common examples are found with up: grow up; get up. Both of these have an idea of moving up – grow on its own could mean any direction, but humans get taller, therefore up. When you leave your bed, hopefully you stand, again, with the idea of going up.
Related to phrasal verbs is the idea that verbs take prepositions, just like in Spanish (example pensar en). Direct translation here leads to many problems. For example, in English we think about, we think of, but we never think in. Also, some of our verbs don’t take prepositions, so for example you talk to your friends but you can’t use your phone to call to your mother. Again, you simply need to learn the agreements. The key to this is practice, practice and more practice.
Finally, for. This is often translated as por or para, but in reality it’s much more complex. Depending on your dictionary, you can find over 20 definitions or uses of for. More annoyingly, it’s not always a preposition; sometimes it functions differently. It’s the word we use in English when we think there should be a word somewhere, but we don’t know which one to use. It’s important that you remember that it’s not a simple translation of por/para, and it’s also not worth trying to remember every exact definition. It’s a good example of the need to get a feel for the language.
So, be careful with prepositions! They’re easy to get wrong, but not hard to get right. It’s also good to remember that making a mistake with prepositions can lead to serious problems in communication. Finally, this even confuses us native speakers: we’re never quite sure whether to fill out or fill in a form!