My French manicures are awful

I have an interview and trade test tomorrow, my first ever one and I've just been practising my French on 2 friends and I was nowhere near happy with it [emoji17] I just can't seem to do it without getting the white all over their fingers which just makes such a mess. Im feeling totally despondent [emoji17]

Any tips for doing the white tips? I use Shellac and I'm happy with everything else just the white tips [emoji35]

Thanks xxx