Kind of hard to answer if we don't know what blemishes you are asking about.
this seems silly, but it totally works. Get a cucumber and "juice" it by crushing it in your hands. Add a few drops of lemon juice and apply to your face. It naturally lightens the skin.
exfoliate regularly and always wash your face. If you tend to have dry skin, wash only at night, and for oily skin both day and night.
And drink lots of water!
When I was younger the best method was not to touch them. That for me fixed most of it. Don't scratch them open, wash your face and hands often. (preferable with cream that dries the skin if you have a fatty skin). Also avoid chocolate, beer, and other fatty foods. Doing sports and sweating a lot can make it worse at the start but after a while it gets better.. But always take a shower after you sweat. (= These are my personal experiences and not scientifically provern or anything).
Lately I came accross a product called: Rain Revri. If you want to watch the videos of the product you can here: http://rainseedexperience.com/revri/. But I never tried this before and I don't know the results for Blemishes. It is just something I came accross which can be helpful in your situation, but don't ask me for details ;). I just had it bookmarked somewhere.
Hope this helps.
Apply a mixture of Honey and cinnamon for a week. This works.