The second one is easily translatable:

Sevig guil erui. (lit.: "You have one single life.")

The first one is a hard nut to crack, though it can be paraphrased:

Nadath sevir i chilu dîn said. (lit.: "All things have their own sources.")

Not the best, but maybe others have better ideas.

+Lőrinczi Gábor if it were Quenya, I could render it perhaps as ilqua xéya tyarwenen "everything passes by a reason". Sindarin, no idea.

+Tamas Ferencz +Lőrinczi Gábor
That could be: Illaid hídar a-chaeth.

il+nad = illad "everything", pl. illaid [for ln>ll, PE19/100]
SKEY+ta = hída- "?to happen"
ᴱkahta > caeth "cause, reason, motive"

Thanks for the help guys. If we wrote it like: " all begins with an intention"? Could it be easier translated? I have no problem to translate it in Quenya.

'everything begins with an intention' could be something like
ilqua horya/*yesta merestenen in Quenya

+Tamas Ferencz thanks

Excuse me, but are you sure that all these translations are correct, because I want make it on tattoo, but with all these translations I can't understand which is the best. I really appreciate your help.

+Βιλλυ Παππα
the vocabulary of these languages is incomplete, so the translations we gave you contain reconstructed words out of necessity, and Tolkien probably would translate them differently if he were here to help us out. So if you are worried about correctness maybe you should leave the phrases in English and just write them out in Tengwar - looks equally nice and you can be sure of the meaning.

ok! thank you very much! so these are the best translations that we have, but I don't know which to choose.