Know your nails
It's easy to put problems with your nails down to many things - washing up in warm water might leave them weak, constantly painting them could cause staining and harsh manicures will leave them flaky. All of that could be true, but sometimes issues with your nails point to other health problems.
The first thing to keep in mind is the colour of your nails. Healthy ones should be pink, and if you notice a dramatic change it could be because you aren't including enough nutrients in your diet. White ones can mean you aren't consuming enough iron or have bad circulation, as generally they are that colour because not enough blood is reaching them. They can also go dark red if you eat too many fatty foods, basically over consuming things like sugar and salt. You may find your nails go a purpley colour if your digestion is playing up due to too much sugar as well.
If yours are taking on a yellow hue, keep an eye on it. It may just be some discolouration due to over painting without a basecoat, but if they start to flake or split it could mean you have a fungal infection.
Another giveaway about your body is the texture of your nails, which can be impacted by anything from your diet to the state of your mental wellbeing. Brittle nails have been linked to liver issues, so try packing your meals with things that are easy on your body like vegetables, wholegrains, garlic and lots of water.
Certain medications may cause your nails to flake, as will over consumption of sugar. And ridges shouldn't be ignored either - if they are horizontal your body might be telling you it's feeling too stressed. Ones which stretch from top to bottom are another sign your liver is being worked too hard.
That being said, ridges also get worse with age so you may find you are just predisposed to them - it's a sign your nails are getting older and probably aren't as moisturised as they once were. Don't buff them away as you may do more harm than good (nails are fragile!), instead try applying nail oil to make sure they are hydrated.