Get familiar with the developer tools in your chosen browser. Learning how to find the CSS style names that ignition is using in order to customize your look and feel is extremely important. Also, make sure you have multiple browsers to test in, sometimes what works in one doesn't work in another and the only way to know is to try.
Also, test in a real browser, some things just don't work the same when run from the designer. Using the designer is a good gut check but the best test is always the browser.
I would also recommend getting comfortable with JSON. Learning to recognize when a JSON string is valid or not comes in handy.
Also, here is a good post that I have bookmarked that really helped me when I was starting to pick up perspective.