Vaseline or flavoured lip balm for the lips – which one will prevent darkening?

Darkening will be only prevented if your lip balm has SPF. That will do for morning time. At night, you can try Liplex. It has depigmenting properties and it’s also enriched with essential oils.

Is the SPF in my foundation sufficient or should I wear a sunscreen separately?

If it is around 30 to 35 SPF, then I think it’s sufficient.

I have burn marks on my fingers from a recent kitchen accident. Nothing too serious but they don't seem to lighten. How can I lighten them?

With time they will. Keep your hands moisturised all the time. You can also try Cicatrix Gel it really helps with the burn marks.

I came across a tip suggesting using argan oil for my hair to control frizz but cannot decide if its best before wash or after. What do you suggest?

You can apply it two hours before shower as a deep moisturiser and few drops after shower to tame down the frizz.

I am 29 and my skin type is normal to dry. I want to make a dedicated investment in skincare. Can you suggest home remedies as well as beauty products that I should include in my new skincare routine? I don't have acne or pigmentation and my under eye bags are HUGE!

Once you hit your 20s it’s high time to start investing in anti aging products. Sunblock is your best friend and a good quality night cream with retinol will suffice for now. You can add on serums to your beauty regime as serums have specialised small particle size good to penetrate deep down the skin. Look for a Vitamin C enriched serum. It’s going to take care of the collagen drop down.