Probably the reason you find it hard starting again is because you put up a mental barrier from doing it. You haven't played for like for weeks or a few months, so your brain thought of the time and effort derusting will take. The only thing you can do about it is to just play, even for a few minutes is fine. Just start getting into the habit of playing again and it'll work out.
For derusting tips, just play normally but at a star rating you're comfortable with and slowly go up in level. Don't get frustrated when you aren't derusting fast enough since derusting will take weeks to months depending on how long you haven't played.