Objectively, we may reach immortality at some point. It might be attained by keeping the body forever healthy and avoiding death factors, or brain data uploading as suggested by some members. However I think it is not good from a psychological point of view. Can an endless life truly be called "life"? If being alive is defined as "not being dead", can life exist in the abscence of the concept of death? And somebody immortal would be mentally unstable, creating a "void" in his person, leading him to have no goals, and wishing his very own death.

Well the best way is to practice as much as you can. For example when I was still young I mastered English by frequenting english sites and using it alot (accompanied with some studies). Right now I'm starting German from scratch using Duolingo, and it is quiet helpful! Of course you must study as much as possible. Other than that I've tried a few other apps and books. But now I'm gonna give Rosetta Stone a try (it seems good).