A serum is the easiest place to add a little glow without rebuilding a routine. I like them thin, quick and unfussy, and there are plenty in that mood.

Merit's Great Skin Instant Glow Serum combines niacinamide and hyaluronic acid, and it gives skin a soft, fresh look right away. Glow Recipe's Plum Plump is a hyaluronic hydrating serum with a bouncy, cushiony feel. Caudalie's Vinoperfect is made for the look of dark spots and is a good switch if vitamin C has been too sharp for you. Eadem's Milk Marvel pairs niacinamide with vitamin C, aimed at the same dark marks. innisfree's Rapid Vitamin C serum is made for dark spots and post-breakout marks, a bright one for mornings.

Sunday Riley's Good Genes is the strongest character on this list. It is an all-in-one lactic acid serum made for uneven texture and dark spots, so treat it as the evening exfoliating step, not something to layer with a retinol on the same night.

To find your favorite, use one for a week and look at your skin in daylight, without makeup. Is it smoother, brighter, calmer. If it is just tingly and pink, it is not the one.

One more habit that helps: apply serums on slightly damp skin, straight after cleansing, and press rather than rub. You use less product that way, and it sits more evenly, which matters most with the vitamin C ones, since they can feel tacky if you pile them on.

A gel moisturizer can suit almost anyone in summer and many people all year, especially under sunscreen and makeup. It should feel like a drink of water, not a coat of paint.

Clinique's Moisture Surge 100H is the classic gel-cream with hyaluronic acid, bouncy and cool. Laneige's Water Bank Blue Hyaluronic moisturizer adds peptides and squalane, so it feels a bit more cushioned. belif's True Cream Aqua Bomb uses hyaluronic acid and niacinamide in a gel-like formula. Glow Recipe's Watermelon Pink Juice is an oil-free, refillable one for shiny days. fresh's Rose and Hyaluronic Acid Deep Hydration is quietly floral, and Youth To The People's Superfood Air-Whip is the fluffiest, a whipped cream that sinks into skin.

What I would skip: putting a gel on top of a heavy cream and expecting it to do more. Gels go on first, or alone. If your skin is very dry, use a lotion or cream over them, and if you wear sunscreen, wait a minute before applying it so nothing rolls into little crumbs.

Also skip judging any moisturizer in the first hour. Look at your skin at the end of the day instead. A good gel should still feel comfortable at six in the evening, not tight, not slick, and it should let your makeup sit where you put it.

Keep a jar or pump near the sink so you use it, since a moisturizer in a drawer is only decoration.

My routine with all of this is quite dull, which I think is the point. Cleansing balm at night, a serum, a gel moisturizer in the morning, and the richer cream when it is cold.

Start with two products, keep the rest on the shelf, and add a new one only after two weeks. If skin stings, peels or turns red, stop and check with a doctor or a dermatologist before you carry on.

If you are tempted to change everything at once, resist. Skin is a slow reader. Two weeks on the same shelf will tell you more than a shopping spree ever could, and it leaves you with a routine you can explain in one sentence to a friend.