Here's my buddy Bob Bergen critiquing other folks attempting to do the cartoon voices he does, most of which are Bob channeling Mel Blanc. We had Bob on The Garfield Show a couple times and he was quite good at inventing brand-new voices on demand, as well. The thing to remember about Bob and someone like him who does "second generation" performances of pre-existing characters is that it's not about mimicry. The good ones — the ones who do major characters — are actors first and impersonators second.
Bob is also one of the best teachers of his art, which is why his classes have waiting lists longer than the lines outside Costco to purchase toilet paper. You can see in this video how well he has mastered the art of saying something constructive and encouraging about performances of varying quality.
I wonder how many of those demonstrating their talents here are aspiring to actually someday get hired to do Porky or Tweety professionally or if they're just out to imitate the voices to amuse their friends and show-off. There's a big difference. I've met lots of folks who could do a great Bugs Bunny when all it meant was repeating a few lines they heard Mel do in some cartoon. That's fine but the guy they hire to do the wabbit professionally needs to be able to, first of all, do Bugs speaking lines that Mr. Blanc never uttered. My friend Greg Burson was Bugs for a while and he was called upon to do Bugs with an Irish accent, Bugs with a Swedish accent, Bugs with a German accent…
And also, a pro has to be able to sustain the voice over many hours at what could be a very long recording session. I'm really good at juggling three balls for around ten seconds…enough to entertain my friends, not enough to be a professional juggler.
If you're interested in getting into doing voices for animation, there's a lot to be learned from this video. You might also see if you can get into Bob's class one of these years. The wait is so long that by the time you're accepted, you may actually be able to leave your house…