This is going to sound incredibly trite but you have to be your own friend and champion before you can expect anything to change. Most people look ordinary. That's a fact. Most people look a bit rough without a bit of effort (brushing hair, moisturising skin etc). Also a fact.
Looking healthy, well and happy is attractive. Most of us are faking the first bit with makeup and the latter with bravado.
If you have severely dry skin around your mouth I'd go to the GP and get it looked at. You may need a steroid cream or a referral to a dermatologist. If it is more cosmetic than medical try adding this serum to your routine m.boots.com/h5/cat_hub?unCountry=uk&path=%2Fen%2FVichy-Aqualia-Thermal-Dynamic-Hydration-Serum-30ml_1457239%2F (I never pay that much and always buy it on offer) and an exfoliating/acid toner. Clarins do a gentle one if acid is too harsh for your skin.
With you hair, would you like a bit of shape? Adding a solid fringe can make a big difference. So does having a sharper cut.
Everyone looks better with blusher and bronzer. Nars are good - if you have a Space NK go and get them to try them on you.
Bobbi Brown is the place to go for eyes and lips. They will show you techniques and colours. Try their truffle colour shadow stick on your eyelids. It's really subtle but will make you look more awake because it is pale with lined eyes and mascara. They also do good non-sparkly bronzer.
I love eyeliner pencils with smudgers on the ends. They just soften the look and obliterate any mistakes. Estée Lauder do good ones and have a safe brown that suits pretty much anyone. Otherwise Bobbi Brown has some good ones but they are stronger tones.
Everyone looks better with mascara because it makes you look more alert and gives definition to your eyes.
Everyone looks better with a nude lip stick. If you're not quite ready for that Clarins do something that's a cross between a lip colour and a lip balm. I'll link in a minute of my post here will vanish due to mobile site issues.
Also agree a good bra is worth looking into. It will make you stand taller, create shape that will make you feel more confident and most importantly it will be comfortable.