Two kinds of will
Handwritten. Written out entirely by hand by the testator, dated and signed. Simple and free, which is exactly why it is the one most often spoiled: typed instead of written, undated, unclear in its wording, or found too late.
Notarial. Made before a notary and registered. It costs money and is far harder to challenge. With substantial assets or complicated family relations, the difference is worth paying for.
Either can be deposited with a notary, which solves the problem of it being found.
The reserved share
Freedom to leave your property is not unlimited. A defined circle of close relatives is entitled to a share of the estate regardless of the deceased’s wishes. These are descendants, the spouse, and in certain circumstances parents.
The size depends on who and how many they are. I will not give a figure here, because it changes with the composition of the family and is calculated on the particular case.
The practical consequence matters: a will leaving everything to one person usually does not take effect that way. The omitted heir can claim their share back.
Which is why the conversation belongs before, not after
If you want to leave something to a particular person, that is planned. There is a difference between a will, a lifetime gift, and a transfer reserving a right of use. Each has different consequences, tax ones included.
The right question is not “how do I write a will” but “what do I want to happen, and what is the safest route to it”.
If you hold assets in more than one country
Then it matters especially that the will works with the other country too. A will made elsewhere may not produce the effect here that you expected.
If you have found a will
Do not act on it and do not deal with any of the property before it has been checked. See renouncing an inheritance, because dealing with assets has consequences.
What I will need
If you are making a will: a list of the assets and of the close relatives. If you are challenging or executing one: the will itself, the certificate of heirs, and the documents for the assets.
This page provides general information and does not constitute legal advice on any specific case. Rights and deadlines depend on the facts and the applicable law.