Fun! I was hoping there was a thread like this for people to share hacks and tricks. Hopefully it catches on and grows; I'm always on the lookout for new ideas!
These aren't exactly revelatory, but I will try to keep it to things other than straightforward "rules."
- If you buy a lip color you don't care for and can't return it, keep it as long as it's still good and use it to mix with other lip colors. Buy little jars made for travel toiletries or beads if you want to keep a custom color on hand or just use a q-tip or sanitary utensil (the end of a spoon or a spatula that comes with a skincare product) to mix when needed.
- Same thing with foundations, as you will inevitably find yourself with a bad color match at some point (do return it, if possible). Consider whether it may be useful for highlighting or contouring, or whether you can mix it into a correctly-matched foundation to accommodate a summer tan. You can also mix it with moisturizer to sheer it out if it's slightly dark or add face oil if it's too heavy and is appropriate for your skin type.
- To get the best results when curling your lashes (if you need to), close the pad on the eyelashes and slowly/gently—especially when you first try (it may seem intimidating)—twist your wrist inward so that the eyelash curler is almost upside down and hold as usual. Continue to do this as you walk the curler in/out on your lashes. (As you get closer to your eyelid, this obviously won't be possible. If you aren't familiar with eyelash curlers in general, I'm specifically talking about the traditional metal kind. And don't squeeze too hard or you'll create strange kinks in your eyelashes.)
- Somewhat obvious, but get creative with your product use/placement—use a lipstick as a blush, a metallic eyeshadow over a dark matte lipstick, an eyeshadow as a highlight. You want to use discretion when putting things near your eyes, but I'll sometimes use blushes and bronzers as eyeshadows or dot a tiny bit of clear gloss or a sheer, buttery lipstick on my lids for some sheen (may cause your mascara to transfer). Same thing for brushes—it doesn't matter what the brush is intended for if it works for other jobs, as well.
- Repack broken compacts/solid powders with rubbing alcohol: break up the product in the compact completely; add a few drops of rubbing alcohol—maybe 10 for a normal compact, you're not going for a liquid or cream (it will dry, regardless, but be impossible to shape); place a piece of wax/parchment/foil over the surface; use a hard, flat, smooth object (e.g. the back of a spoon, a quarter, a pestle) to compress the product and reshape; let it dry for a couple of hours so any moisture evaporates.
- If you find yourself with a dried-out mascara—screw those tops on—and don't have time to buy a new one before your day starts, try running the tube under hot water or adding a couple of eye drops.
- Try tracing a clear wax pencil (like the ones made for eyebrows) lightly around your lips to keep your lipstick from bleeding if you don't have lip liner in the right shade/at all/it isn't working.
- Make your own color-switching brush cleaner by taking a clean tea tin or other small, round container and sticking a hair donut inside. (Don't forget to wash it. And your brushes.)
That's all that's coming to me right now. As far as a few words of general advice: don't try out a new look for the first time right before you have to be somewhere important, remember you can always add and too little is preferable to too much when it comes to makeup, undertone suggestions are not rules (but do match your foundation and concealer), WEAR SUNSCREEN EVERY DAY!, wash your face every night (and use a towelette or micellar water when you tell yourself you will but you know you won't), introduce new skin products slowly if you are sensitive or prone to breakouts (easier to identify the cause).