1) Whether or not your mother tongue and the foreign language you're learning have a shared lexical family and glossary (Latin or Germanic languages for example)

2) Your own ability to assimilate new words and think in the new language, rather than translate everything in your mother tongue, translating everything to the new, foreign language afterwards

3) The amount of contact you're receiving with that particular language, externally (for example, English is a lot easier to learn than other languages for most foreigners, since they receive a lot of external contact with it from movies, computer activities, commercials and so forth).

Regardless of the fact that the language you're trying to learn fits into any of the above categories, make no mistake about it, every language is learnable if you follow a few important steps and if you invest a constant stream of time in the learning process. Taking medium to long breaks from learning will be extremely negative in the long run, since it will be harder to get back on track and "re-learn" what you've once assimilated. Think of learning a foreign language as taking care of a huge furnace. You need to place a huge amount of coal in it in order to get it started and then you need to keep the fire burning by constantly shoving medium amounts of coal. If you stop shoving and let the fire go out and the furnace go cold, you'll have to invest almost the same amount of work to get it back on.

So you might be wondering how to start learning a new foreign language, what should be the base point for the learning process. Well, some basic vocabulary will get you started with understanding and pronouncing the language as well as give you something to work with later on. Language learning games are extremely useful in this first stage, since the correlation between images and words will get them to print easier in your mind. Using flashcards is also a good option and although learning what "duck" is in German for example, might not be that satisfying, think about the fact that the whole game thing has a higher purpose. And if you're an adult, try getting past the inherent awkwardness and silliness of this first learning stage as it is proven to be one of the most efficient yet. And who knows, you might even have some fun while you're at it :).

After you're familiar with the new language, after trying out pronouncing what you've seen on the flashcards, or in the game (by the way, always keep a "mother tongue - foreign language" dictionary close to you, since you'll want to check on pronunciations often) you should start off with a couple of translated texts that you can compare. Don't worry about the subject, reading "Little Red Riding Hood" with the annexed translation will be equally helpful as reading a technical view on computer architecture with the relevant translation (actually Little Red might be even more useful, since it will be easier for you to relate the words). Try reading the foreign text, sentence by sentence and then re-reading it in the translation. While doing so, try and spot the similarities in grammar and sentence structure and focus on noun gender, and plurals. It's extremely helpful to get used to the new language's gender and plural system early on or you might get the "habit" of mixing them up, sounding funny at best.

The above-mentioned method of learning a foreign language might not necessarily be the one most appropriate for you. Still, it simulates the way we learn our mother tongue, which makes it easier for us, your brain adapting easier to the new learning process since you've "already been there and done that" once. If you're looking for alternative ways of learning a foreign language, be it Spanish, German, Japanese, Italian, Dutch, Portuguese, Romanian, Turkish, Hindi, Polish, Greek and many more, you could look up one of the many sites out there offering free or paid lessons and tutoring services.