1. Getting your photos in National Geographic is a dream for most photographers. While you'll have to work hard to achieve that goal, photographer Bob Holmes has some great tips to emulate the NatGeo style. I mean, who better to get photo composition tips from than a four-time Travel Photographer of the Year award-winner?
2. Photography can be a money pit if you let it. Luckily 500px posted a great guide on The Best Ways to Invest Your Money as a Photographer. It's a great place to learn how to get better as a photographer.
3. Filters can really help you get the image you want, but it's confusing at first to know which to buy and when to use them. DPS has an excellent guide to the Introduction to Filters for DSLRs.
4. Noise reduction for night sky photos can be tricky, because you'll often remove the stars from your photo with the noise. Photographer Dave Morrow has a simple method for keeping your stars intact. A Simple, Effective Noise Reduction Technique for Night Sky Photos.