Assuming you already know other languages ... Pick a smallish but difficult problem, and solve it. Maybe best is to make a personal utility that you would use,

Assuming you already know other languages ... Pick a smallish but difficult problem, and solve it. Maybe best is to make a personal utility that you would use, even if you already have that utility. Don't worry about getting every idiom right, or fitting in exactly with the language's culture (but do pay attention to it). Try all the things! This is your chance to try all the language features, without embarrassment, even if they aren't the most appropriate choice. Get something working the very first day, preferably the first hour. Could be the equivalent of hello world, doesn't matter. Always have something working, and something next on the list for tomorrow, to help you wake up interested. That way you'll keep at it.