The Basic Recipe!
As mentioned above, French meringue requires only two ingredients: egg whites and caster sugar! The ratio you'll need of each is also very straightforward; that being 2:1 caster sugar to egg whites. As such, I recommend that when you prepare your ingredients, weigh out the egg whites as you separate your eggs so you'll know exactly how much sugar you should be adding!
As an example, if using 4 medium eggs, your recipe may look a little like the following:
135g egg whites
270g caster sugar
If you are looking for a vegan version of this recipe, you can swap out the egg whites for an equal amount of aquafaba, which is simply the strained water out of a tin of chickpeas! It will whisk up in just the same way as egg whites do and, while the resulting meringue may be a bit more fragile than the egg-based equivalent, the method you need to follow is exactly the same, making it really easy to cater for your vegan friends and family!
In terms of sugar, I would personally stick to using the regular, white caster sugar. Golden caster sugar can give your baked meringue a bit of golden hue, which sounds romantic but can appear as if overbaked, so I'd say you'd be better off colouring the meringue with some gel food colourings to achieve a more accurate colour. You will want to avoid using brown sugar for this recipe, as the molasses in the sugar will be released in the oven, introducing further liquid into the meringues we are trying to dry out.
Finally, as an optional extra, I like to add a little vanilla extract to my meringue to give it a bit more flavour, typically 1 tsp for every 4 medium egg whites used. You are welcome to use any extracts or essences you fancy; if using them as decoration for a cake or other bake, perhaps you could flavour the meringue in a complementary way!