One question I am always asked is if I can only buy one product what should it be? Unfortunatly there is no easy answer as make up is individual as the person wearing it so there is not a 'one size fits all' product. If you are struggling for time in the morning (who doesn't?) I suggest spending some time to really assess your face and think about your features what you might need to conceal and what you think you can get away with.
Sit down with a mirror and look at your face shape, hairline, features, skin type and lip/eye colour. For me I don't go anywhere without my blush and a slick of mascara but my skin and lip colour is quite vibrant on their own so can often skip the stage of applying a heavy foundation and prefer a lip balm to spending time on liner and lip gloss. A good bronzer can be used as a bronze, contour and eyeshadow all depending on how it's applied. Highlighters can be great for using on lids, cheeks and eyes to give you a fresh faced look (try the classic Benefit HighBeam). If it's your skin you need a bit of help with invest in a really good foundation or even mix some of your foundation with a luminating face cream (my favourite is MAC Strobe Cream which is also a great alternative to primer if you don't want to splurge try Olay's Complete Care Multi-Radiance moisturiser).
We all need a bit of pampering and some salon treatments can be really beneficial in your time saving efforts. Eyelash and eyebrow tinting are a great way of saving your precious time on applying mascara and filling in the all important brows. Regular facials can help the skin look more radiant and keep up your water intake. Keep lips buffed by giving them a rub with a towel or your toothbrush a apply a lip conditioner. Finally try and give your nails a buff and polish atleast once a week.
Good luck ladies time is precious but for me it's time well spent!