I have realized that there are two main essential things to keeping your pores clear: the right cleanser and the right moisturizer.
The only cleanser I have found that actually cleans out my pores is the Emma Hardie Morigna Cleansing Balm. If I keep this cleanser on for at least 10 minutes, when I wipe it off I notice that my blackheads are a lot lighter. Not gone, but definitely a lot less noticeable. Any other cleansing balm might do the trick, though I do swear by Emma Hardie.
The second key to keeping your pores clear from blackheads is using a good, light moisturizer, specifically one without mineral oil within the listed ingredients. Mineral oil easily clogs pores and is therefore a big no-no for a moisturizer to be used on your nose.
I have two moisturizers that are both great options. Simple's Clear Skin Oil Balancing Moisturizer is a great choice for keeping your nose clear, especially if you have an oily t-zone. Another option that I've been using is by the brand Alterra, which is organic and therefore contains only natural ingredients.
These two things combined help prevent blackheads from forming :). Hope these tips are helpful!