Especially if it doesn't come naturally to you, getting good at design takes a ton of practice. But if you do practice, you can definitely improve your design sensitivities and skills.
Make sure you're getting feedback--and not feedback that says "I like that" or "I don't like that". Specific feedback is really really essential to improving what you're doing.
Purpose and focus
I think purpose and focus are the key to a good design. Never do something without a reason. Remember that the reason you're doing design, at a very high level, is probably not to make something pretty. It's to help whatever you're designing better accomplish its purpose. Making pretty might be (and likely is) part of that, but it's not all of it. Always keep that in mind.
Typography
The other stuff mentioned here is also essential to know, but don't forget type. Type can (and will) make or break a design. I recommend taking a look at Typography for Lawyers (http://www.typographyforlawyers.com/) to get a start, even if you're not a lawyer. It has a good overview of a lot of the things you need to be thinking about, and you can ignore the lawyer-specific details. Type, like everything, takes practice. I recommend finding a couple of fonts (1-2 sans-serif, 1-2 serif) and getting very familiar with them.
If you'd like more help, or feedback on something you're doing, feel free to send me an email--it's in my profile. I'm far from an amazing designer, but I am pretty good at giving feedback.
Especially if it doesn't come naturally to you, getting good at design takes a ton of practice. But if you do practice, you can definitely improve your design sensitivities and skills.
Make sure you're getting feedback--and not feedback that says "I like that" or "I don't like that". Specific feedback is really really essential to improving what you're doing.
Purpose and focus
I think purpose and focus are the key to a good design. Never do something without a reason. Remember that the reason you're doing design, at a very high level, is probably not to make something pretty. It's to help whatever you're designing better accomplish its purpose. Making pretty might be (and likely is) part of that, but it's not all of it. Always keep that in mind.
Typography
The other stuff mentioned here is also essential to know, but don't forget type. Type can (and will) make or break a design. I recommend taking a look at Typography for Lawyers (http://www.typographyforlawyers.com/) to get a start, even if you're not a lawyer. It has a good overview of a lot of the things you need to be thinking about, and you can ignore the lawyer-specific details. Type, like everything, takes practice. I recommend finding a couple of fonts (1-2 sans-serif, 1-2 serif) and getting very familiar with them.
If you'd like more help, or feedback on something you're doing, feel free to send me an email--it's in my profile. I'm far from an amazing designer, but I am pretty good at giving feedback.