Referring to myself as an older sister

I am writing on a Christmas tag for my little brother:
おとうと
Love from
(Big Sister)

Do I write ane or one Esan for big sister because I am talking about myself but not to myself?
I have written Oneesan to be safe for now.

Thank You!!!

Ane (姉) is more appropriate, assuming that your brother is not too young.

You should write "Love from お姉サンタ" or "Emiさんタ(エミさんタ)".
= Onee-san(お姉さん) + Santa Claus(サンタクロース).
https://goo.gl/gRVQis
https://goo.gl/uxMT17

The proper way to write is "ane," you are referring to yourself, so you don't use the honorific "o-" or "-san." But just writing
Ane (big sister) by itself at the end sounds/looks a bit blunt, so you could write:
"Ane yori" (from your big sister)

Or if your younger brother (and you) are quite young, you COULD write:
"Neesan yori" (from your big sister)

Actually, you don't call your younger brother おとうと. When you're speaking to others about your brother you use the term. For example, you can say, "おとうとが、いえに、います (My younger brother is at home.)" But when calling directly to your younger siblings, you use their names.

Meanwhile, typically, older siblings sign themselves in the way the younger sibling calls them. For example, if your brother calls you "oneechan" you sign "oneechan yori" ("yori" means "from"). If he calls you "neechan" you sign "neechan yori".

If he doesn't specifically call you in a Japanese term, or if you want to write it in a proper form, you use "ane" as suggested.

So let's say your brother's name is John. ”Love" is "ai", so my suggestion would be:

ジョンへ
あねより、あいをこめて

Hope it helps. Merry Christmas!