The best way to get good at design is to practice a lot.
For example, I'd recommend not using Twitter Bootstrap until you're comfortable doing it all the hard way. It will take time when you start, but over the long run you'll be in a much better position if you know your CSS and know how to make it all look good.
On the latter point, create a favorites folder called "Well Designed" and save pages to it that appeal to you. Take a few seconds and ask yourself what about it makes it look good. Inspect elements using your browser's built in inspection tools and see what the developer did to make it look that way. Then try to do it yourself and repeat.
For example, I'd recommend not using Twitter Bootstrap until you're comfortable doing it all the hard way. It will take time when you start, but over the long run you'll be in a much better position if you know your CSS and know how to make it all look good.
On the latter point, create a favorites folder called "Well Designed" and save pages to it that appeal to you. Take a few seconds and ask yourself what about it makes it look good. Inspect elements using your browser's built in inspection tools and see what the developer did to make it look that way. Then try to do it yourself and repeat.