In France, all shares must be attributed at the time of the company’s incorporation.
Thus when writing your bylaws, you must foresee an amount of share capital and the number of shares.
To start, madeinlaw.com suggests 10.000 shares by default as most of the US companies, and as you increase your capital amount, the nominal value of your shares will increase if you keep the same amount of shares.
Why 10,000 shares?
The number of shares in your company is relatively unimportant at the beginning, nonetheless, the current trend for startups is to give shares to the employees. It allows employees to contribute to the success of the company. It’s always more engaging for future employees to have shares that are counted in the thousands (even if their value is negligible) than in the dozens.