Steep water with a bunch of mint leaves, cool and drink it all day.
For the acne marks u should see a derm and get a prescription for HQ which stops the production of melanin.
For blackheads, use a good face scrub 2-3 times a week.. baking soda mixed with a little water.. left on the affected area for 20 mins works well (rub-it off like u'd use a scrub)
U can apply ice to temp shrink u're pores and after cleansing always use a non-alcoholic toner.astringent.
To avoid furthur damage invest in a GOOD sunblock meant for u're skin.
Once a week use a deep cleansing face mask (neutrogena is great)