When I apply liquid eyeliner, rather than following the curve of my eye just from the inner corner to the outer corner, when I get to the middle of my upper lashline - the highest point of the curve - I simply continue my eyeliner out in a straight horizontal line to the edge of my eye. And then I make a line from the outer corner of my eye to the end of that horizontal line and fill in the space. This creates a perfect flick every time, and is a good way to make sure my eyeliner is even on both eyes.
Lip liner doesn't have to just line the edges of your lips. If you're wearing a bold colour, which is all the rage this summer, fill in your entire lip with a liner that's a similar colour to your lipstick. Leave it for a minute, blot it with a tissue to remove excess product and then apply the lipstick on top. That will help the colour last longer, and even though the lipstick will wear off before the liner, the base will stay put, giving you plenty of time to reapply.
I think nude or pinky-nude nails look great with anything, but pale nail polishes always streak when you apply them. It's hard to find a formula opaque enough not to streak. So instead of a standard base coat, I paint my nails with a matte top coat, and that acts as a great base for any nail colour. It helps the mani last longer too!
I also have an old angled make-up brush I no longer use, and I use that, dipped in nail polish remover, instead of cotton buds to clean up my manicures. It's more precise, and wipes away messy nail polish perfectly.
Gold eyeshadow, or liner, in the inner corners of your eye, whatever your skintone and whatever other make-up you're wearing, somehow detracts from the fact you were staying up until 4am reading or rewatching all nine episodes of Sherlock. It brightens that area and makes you look more awake.
I'm a stickler for luscious lashes. To get them, I apply one coat of mascara and let it dry before adding another coat. And to prevent spidery lashes, I use an eyelash comb to separate them. Its teeth are thin enough to get between each individual lash.
To make sure that my powder blush or bronzer stays put all day, I apply my setting powder first. This creates a stronger base for the other powders to hold on to.