Everyone has made a lot of mistakes when applying make-up, myself included, but a lot of the time we don't actually that we did so here's the things that I noticed that me and other girls do. Recommadations are in bold. 

1. Wearing the wrong shade of foundation - I've seen many people wear foundations that are obviously darker than your skin tone, fondation is made to cover up any imperfections not give a tan that's what a bronzer is for. When you buy a new foundation, make sure it's actually your skin colour (the shades typically go like this: Porcerlain/Ivory, Light, Medium, Dark) also try it on your jaw line not the hand (although I admit I do that alot) because the lighting may change on various parts of your body but your only interested on you face.
2. Applying Make-Up on Dry/Flaky Skin - Seeing foundation over dry skin can look awful as it actually emphasizes the flakes when it's on them instead of being blended into the skin. To fix this, I would use an exfoliate and use it regularly to get rid of the flakes and use a moisturizer after, this will smoothen your skin and give it a more finished look.
3. The Eyebrows - This is true, the eyebrows can actually enhance your eyes and whole face and make it look more attractive (not saying you aren't) and you don't want to tweeze overgrown brows too much so the best thing is to just stick with cleaning the area around the brows and follow their natural arch.

For the second mistake, I would recommend using the 'Dove Rich Nourishment Cream' and the 'Cien Daily Exfoliating Facial Wash'. I honestly use both of these and they are good but you may not think so. However, you could give them a try and see how you feel. 

However, here are some more exfoliants:

• Nivea Exoliating Face Scrub
• Clean & Clear Exfoliating Face Wash
• Garnier Exfoliating Face Wash
• Tea Tree Exfoliating Wash (<--- good for removing dead skin cells that cause Acne)