Have a theme which truly interests you.
Concentrate on triggers first, not object data.
Make friends on bnet with who you can test your map when it's in development.
Ask for help with a trigger on
WEHZ, if you face an impassable obstacle.
Have internet browser on half of your screen, WE on other half.
Watch a lot of entertainment on internet browser while developing.
Don't develop when hungry, grab a microwaveable pizza or something.
When feeling like it, go outside for sometime (at least 20 mins), it makes you feel motivated.
If there's tv in your room, have it open. Mute it when not interested in it, unmute when you wanna quickly relax.
Don't use time schedules for developing.
Don't load your map full with custom resources before it's ready.
Get the first version out asap.