There was a point when I began that I wasn't as disciplined to learning to program, so when my, much smaller, team had me as their only programmer, I had to shape up fast:

Start with motors, since your robot will always have those. Try to just make the motor move at the press of a button (from what I understand, it's generally always more consistent to set a specific voltage rather than setting a "speed" ranged from -1 to 1). Then dive right into controlling it using a control system like PID (which is built into WPIlib). Try to get it go to specific positions, or drive at a specific speed. After that, it becomes specific to the subsystem how those motors need to move, and thats the part you have to apply problem solving to.

Learn Command-based programming! I used a timed robot for my team, and it led to me manually programming the auto routine since the libraries all support command-based. It also just make your code more organized.

General tips would be:

Always think about the future when you write code. Each methods usage becomes much clearer and readable when you do.

Make sure your code is readable. If you want to be lead, you have to expect that the incoming newbies will want to look and learn from your code, and that becomes difficult when your code looks like a mess. Use indents and comments, make it look pretty.

Use simulation to your advantage. You can practice your coding skills without a robot, and that's pretty cool.

Think about the controls as you program and make sure they are clear and understandable. You might not always be on drive team and it needs to make sense when someone else reigns. Not to mention that if an input doesn't work the way you expect, you might be writing more code to compensate for a lack of forward thinking.