I need an Accurate translation from english to italian! HELP?

I want this tattooed on me permanently so please be as accurate as possible...i've tried bing google and yahoo translations and when i reverse the translation it is way off! This is what i need translated...The greatest thing you'll ever learn is just to love and be loved in return.

Thank you:)I need an Accurate translation from english to italian! HELP?
La cosa pi霉 importante/ fantastica / magnifica /meravigliosa / grandiosa / bella che potrai mai impare 猫 (semplicemente) quella di amare e di essere amato.

There is no accurate translation for "great", literally it's "grandioso" but I think that "great" has a broader meaning in English. IMO "bella" is the simplest and probably the best, importante sounds good too but has a slightly different connotation, as in "important".
The translation I gave you uses the masculine form, which in Italian is also meant to be used as neutral form, but in fact you can't help but think it is referred to a male. You could use impersonal verbs instead.
I would skip translating "just": "semplicemente" is too long and makes the sentence heavier, "solo" is short but I think in Italian has a connotation closer to "only" than to "just".

That's the translation I find more suitable for a tattoo:
"La cosa pi霉 importante che si possa imparare nella vita 猫 quella di amare ed essere amati."I need an Accurate translation from english to italian! HELP?
La cosa pi霉 grande che tu possa imparare 猫 solo quello di amare ed essere amati in cambio.
the answer above me is missing "just" so yeah you can check mine :}