The following has some great tips for beginner modellers. Especially interesting is the article on blackened muzzle brakes.
http://www.panzerworld.net/models.html
I like that site, I tend to agree on the muzzle brake deal. I felt this feature was way over done on the two pre-built DML Tigers I purchased recently.
I do add a little toning to the inside of the muzzle brake to suggest some use and to get the thing to stand out a little better. But I don't like to see a foot or so of the end of the gun blacked out.
Rick
Excellent - thank you Bernie.