You cannot just translate every single word literally into another language getting the same effect or idea, because there are sometimes different meanings to similar words and so-called false friends. You have to study the correct idiomatic expressions or phrases. Particularly, when translating rhetorical ways of speaking, images, proverbs, and so on.
It may be „raining cats and dogs“ in English, but there are no animals falling from the sky neither in German nor in Italian. In German „es regnet aus Kübeln“, which is similar to „rain is bucketing down“. The German word „sensibel“ means in English „sensitive“, whereas „sensible“ means „vernünftig“, which is the word for „reasonable“.
Sometimes, we adopt words from the other language and use them as if they were proper words of one’s own mother tongue. You come across a lot of those words when speaking about sports. The short form of „goalkeeper“ is „goaly“ in English, but it is „keeper“ in German. A „mac“ is a kind of rain jacket in England, but it is used as „Mac Do“ an abbreviation for „McDonald’s“ in Germany. Young people also use the expression „mäckes“. „Date“, „soap“, „skater“, „event“, „location“, „open-air“ etc. have been regular elements of the German language for a long time.
Languages of Roman origin like French or Italian are more reluctantly accepting anglicisms in their own native tongues, though many English words are of Latin or Greek origin, which is particularly true with prefixes or suffixes like „pre-„, „anti-„, „-able“ and with a double set expressions for almost the same thing such as „city“ of French origin (la cité) compared to the Germanic word „town“ or „-borough“ which is similar to the German „-burg“ meaning „fortress“ or „castle“ which derives from the Roman word „castellum“.

It will be totally different when learning languages that are not members of the so-called Indo-European family, such as Arabic, Finnish, Hungarian, Swahili, or Asian sign languages with totally different grammar rules and totally different word formations plus different sounds produced somewhere in the throat. Even Celtic or Gaelic is hard to learn for people who do not live in Scotland, Ireland, Wales, or Britanny. German at least has some features in common with these Celtic languages such as the pronunciation of a guttural „r“. Swiss people can even do better and sounds as if they were speaking with a sore throat all the time.

Grammar rules can be so different as well as spelling. There are already differences in the spelling of British and American English. The use of tenses like „Present Perfect“ and „Past“ is tricky. In German, the „Present Perfect“ (Perfekt) belongs to the tenses of the past whereas in English and Italian it has a reference to the present. This is important to know when using reported or indirect speech: Mike’s father has said: ‚I don’t want a new car.‘ => Mike’s father has said, he doesn’t want a new car. / Mike’s father said:’I don’t want a new car.‘ => Mike’s father said he didn’t want a new car.

The present perfect tense is not used a lot for past actions in American English. British: she has watched it ever so often. American: she watched it ever so often.

In Italian, we have the „imperfetto“ which refers to the past, but as it is „im-perfetto“ it means that something in the past was not yet „perfetto“, not yet „finished“ at a certain time in the past. Thus it refers to regular actions in the past or to an action that was just going on at that moment when something else happened. If you want to underline that it was a singular and finished action, you have to use a different form of the past „passato remoto“ or the „passato prossimo“ which is the equivalent to the present perfect tense in English.

In Germany, people in the northern parts use the past tense correctly when speaking about past actions whereas people in the southern parts of Germany tend to use the present perfect tense. „Letzte Woche fuhr ich nach Hamburg und schaute mir ein Musical an“, the southerners would say „Letzte Woche bin ich nach Hamburg gefahren und habe mir ein Musical angeschaut“. The verb forms used by the southerners are easier to remember, but the correct verb forms of the past tense sound more impressive and hard to learn for southerners.

It is similar in Italy where southern Italians master the correct forms of the „passato remoto“ whereas the northern Italians tend to avoid these more complicated past tense forms. „Andammo al mare e mangiammo pesce crudo“ (When went to the sea and ate fresh fish) sounds much better and more powerful than „Siamo andati al mare e abbiamo mangiato pesce crudo“, apart from the fact that the „passato remoto“ would be grammatically correct.

To sum it all up, please always try to pick up the idiomatic expressions. Learn them „straight from the horse’s mouth“ i.e. from native speakers or listen to radio and TV commentators or just read a great lot of books or listen to songs sung by real native speakers. As you can use the internet, „smart“ phones, and e-books easily nowadays, you will find all sorts of authentic material. Get into contact with native speakers using e-mail, social networks, virtual chat rooms, and above all: spend as much time as possible in the countries where the language you want to learn is spoken! Learning by traveling, viaggiando s’impara, Reisen bildet.