Under the microscope: Skinceuticals Hydrating B5 Gel (£35, www.skinbrands.co.uk)

In theory: If cleansing, toning and moisturising seem like hard work, there's bad news: current beauty wisdom has it that three steps aren't enough for perfect skin. Whatever your concern – ageing, dryness or even oiliness – the best way to beat it, they say, is with a pre-moisturiser serum or gel, the idea being that lighter formulas penetrate deeper than the thick emulsion of a standard moisturiser. This gel promises to "maximise the benefits of your daily moisturiser" thanks to the latest wonder ingredient, hyaluronic acid, a natural polysaccharide that aids the hydration and nutrition of tissue.

In practice: The gel looked and felt like water – no bad thing given H20 is what this product is about, but alarming when it costs £2 per ml. Instantly absorbed, my skin felt slightly tight straight after use, but needed less of my usual moisturiser.

Observations: The gel made a significant difference to the look and feel of my combination skin. Ordinarily, moisturiser sits on the surface, leaving skin in the worst of all states – dehydrated yet oily. But the gel seemed to deliver deeper hydration that simply needed to be sealed with a thin layer of moisturiser.

Analysis: If you are concerned enough to be cleansing and moisturising, adding this step shouldn't be too much of a chore. And while it is a pricey addition, I've been disappointed by enough expensive moisturisers to think that buying a serum and going for a more modest moisturiser is the canniest use of your resources.

Prescription: If you've survived this long without using a serum and have been genetically blessed with great skin, the extra outlay probably isn't worth it. But if you suffer from any specific ongoing complaints, a daily pre-moisturiser gel or serum would be a rewarding investment.

Further experiments: French skincare gurus Darphin make three excellent serums specifically for moisturising, mattifying and nourishing, from £45 (www.darphin.co.uk), while Purity Project's Face Firming Serum is a botanical, cruelty-free alternative for sensitive souls and skins (www.purity-project.com).