When you buy a pastel coloured nail varnish it never looks the same on your nail as it does in the bottle. Even if you apply 4 or 5 coats you will still be left with an uneven finish.
In particular if your nails are all slightly different lengths like mine your white tips will also vary in length. I also have a penchant for fake tan so my white tips are stained brown and even with pink nail varnish still look yellow-y.
If you want nail varnish to look truly even and professional you need to approach it like you would a wall and give it a base coat. The white colour that you would use for your tips in a French Manicure is perfect as it opaque and matte. Apply one coat of the white to the entire nail thinly to start. After that you can apply your pastel shade - pale pink like here or beige for a camel-coloured shade I like. I like to apply this coat when the white is still slightly tacky so it almost 'picks up' the white colour. Allow this to dry thoroughly before applying one final coat of the colour to finish. A chip resistant clear top coat too if you can be bothered.
Another way to create this effect is to pour a little of the white into your coloured nail varnish. I love Boots' natural collection because they are just so cheap - less than £2 - and have really good brushes to apply with. Also I don't know if it's because they are in a smaller bottle, but they don't tend to go as thick and lumpy as some more expensive brands. I'll upload my top tips for the perfect French Manicure soon.