Without further ado, the first tip.
Clean your iron. I know that sounds so basic, but seriously. If your iron is dirty, your projects will show it. Here's an easy way to clean your iron and you probably have the things you need already.
Use a dryer sheet when your iron is hot and carefully (don't burn your fingers) wipe off the iron. You'll be surprised at how much build up comes off. I use Kirkland brand dryer sheets, but it doesn't matter what kind.
Then iron a rag or something that really doesn't matter. The dryer sheet leaves a little oil film on the iron, so you'll want to simply iron that off onto a rag. That's all. Go ahead, try it.