I have been pretty obsessed with liquid lip color lately, and that has meant lots of trial-and-error of what does and doesn't work for making my color last all day. What I've found is that no matter how expensive the lip color, it all comes down to how you prep your lips before application. So without further ado, here is what I've been doing that keeps my liquid lipstick on from the moment I first apply it to when I take it off at night.
Think back to what you know about facial skincare - it's important to exfoliate to remove dead skin cells, right? Well, the same applies to your lips - especially if you're like me and you chew on your lip throughout the day, or during the colder-weather months. 2-3 times a week I scrub my lips with a simple sugar scrub and it helps keep my lips smooth (the scrub I use came as a free gift and I can't remember with what - but regular sugar will do, or they sell a bunch of lip scrubs now-a-days).
Before I apply my liquid lipstick, I apply some lip balm or serum to my lips, and let it sit there for about 5 minutes - usually as I'm finishing up the rest of my makeup routine. This puts a burst of moisture into your lips, and will help keep them from drying out during the day. Most liquid lipsticks are matte, which tend to wear on the drier side - so definitely don't skip this step! Any lip balm you have will work - I have naturally wrinkly lips so I like to use a lip serum with collagen to help combat wrinkles. I apply it to my lips, leave for 5 minutes or so, then blot off the excess with tissue. At this point, your lips should feel moisturized but bare - there shouldn't be a sheen of any product left on your lips.
Take a small amount (and I'm talking s-m-a-l-l) of your foundation, and smooth it over your lips. This will leave your lips a slightly lighter color, but they shouldn't be super saturated. This will help the colored liner and lipstick you're about to apply look truer to color - you're essentially toning down the natural color of your lips.
Additionally - the foundation will give the liner and liquid lipstick a little something more to grab onto then just your bare skin.
After your foundation has had a few seconds to dry, go ahead and in your top and bottom lips with the lip liner of your choice.
Hint: using a color lighter than your liquid lipstick will make the liquid lipstick appear a bit lighter/brighter, and using a darker color liner will do the opposite. This is a great way to get multiple looks out of one lip color. If you don't want to change the color, I'd recommend finding a nude shade that is within one shade of your natural skin color.
#5 Apply Conservatively
I saw the biggest difference in the longevity of my liquid lipstick when I applied super thin layers of product. Liquid lipstick is usually super saturated, so you really only need 1-2 coats at most. In order to achieve a thin enough layer, I use a lip brush and not whatever applicator comes with my liquid lipstick. I take my lip brush, pick up a little bit of product from my lip color's intended applicator, and apply just enough to cover my lips. Usually that's enough - but if there are any patchy spots, I'll repeat this process 1 more time.
#6 Leave Your Lips Alone
Once you've applied your liquid lipstick and it's dry - try not to mess with it throughout the day. For example, I have a habit of rubbing my lips together. This can cause your liquid lipstick to appear cakey/clumpy, and make a harsh line at the waterline of your lips that's hard to blend.
I also try not to add any products on top of my liquid lipstick, like lip balm. If your lips are really in need of the moisture throughout the day then go for it - but make sure you tap it on with your fingertip, and let it completely soak in before you eat or drink anything. A liquid lipstick topper (gloss, balm, serum, etc) will make your liquid lipstick tacky and it'll transfer/smudge way easier.
If you do need to give your color a touch up (for example, after you've eaten) - tap on new color with your finger tip, ONLY in the areas that need it. Too much layering can make everything a dry, clumpy mess.
This is probably the most important one - especially if your lips are on the wrinkly side like mine. The more hydrated you are, the more naturally moist your lips will be, so they will feel less dry. If your lips are more hydrated, they will appear less wrinkly and there's less of a chance your liquid lipstick will crack or settle into the wrinkles.
These steps really do work, people! For context, here's a picture of my freshly applied liquid lipstick at 8:30 in the morning, and then at 8:00 at night (after a cardio session, too!).