1. Use what you feel comfortable with--eventually. Some people use markers or ballpoints or copy paper, some even use a dowel rod. There's no one correct way of executing anything. But it's best to start with conventional tools first. Start with india ink, bristol, T-square, gummy eraser, comfy chair, blah blah blah, just like everyone else more qualified than me will tell you.
2. No halos. My own pet peeve. Even some of my favorite cartoonists do it. I can't stop you. It really bothers me when a person or object is standing in front of a black background with a white outline around them. It suggests you're passive-aggressively trying to impress people with the quality of your line. If the thing in the foreground is also black, maybe have some kind of light shining on it to make it stand out, but don't make it look like it's glowing in the dark. Don't get me started on balloon tails crossing.
3. Keep a sketchbook. You never know when an idea will hit you out of nowhere that you'll forget if you don't write it down. It also keeps you in practice. If you don't draw something new every day, lack of drawing will become habit and you might not be able to recover. It's like when guys are told their dicks will fall of from atrophy.
4. Use blue pencil. Computers may make one more lazy, but that's the drawback. I can't tell you what tools to use or not, that's something to figure out for yourself. The blue pencil is something everyone should have though. It won't show up on scanners and you can make mistakes without having to erase them. Everyone should use one.
5. Take from sources. A more polite way of recommending you steal. Not plagiarize, but don't be afraid of being derivative. Kliban begat the Far Side, Doonesbury begat Bloom County, Simpsons begat Family Guy, the influences may be blatant but whether you like them or not they're original in their own right. Kirby is derived from Shakespeare which is derived from Greek tragedies which are in turn based on tales told by cavemen, and on and on. There's no such thing as an original idea when it comes down to it, so you don't have to be a major innovator to be considered unique.
6. Follow the grammar of comics. Use panel borders, gutters, and the like, and call them those things, no matter how corny they might be. Don't show off. Just like the English language requires certain parts of speech and punctuation used properly, so too does comics.
7. Market not only to comic fans. People often tell me something like “My favorite comics are yours and Batman.” It's the subject matter that should resonate, not the medium. Nobody assumes because you listen to a certain kind of music, you listen to everything just because it's music. Is your comic like Breaking Bad? South Park? Dancing with the Stars? A Woody Allen movie? Pick something you feel is similar to yours, but the common ground should never be that what you do also has words and pictures made with ink on paper.
8. Don't work for free. It's okay to do free things for friends or students. Just don't heed the promises of strangers who say they will give you “exposure.” Cartooning is a job like any other. Just let these people try telling their printer, post office, landlord, etc. the same conditions and see where that gets them.
9. Don't care what people think. No subject matter is off limits. This isn't to say that you should sit down and think “what can I do that will offend people?” Just that you shouldn't care if it does. A tragedy for some is just a statistic for others. Not to suddenly become a sociopath, use the same boundaries you always have. I may find some things may not be appropriate, but don't censor yourself because I say so.
10. Do as I say, not as I do. Let's see, what other corny sayings can I use? “Those who can't, teach.” “You have to get 1000 bad drawings out of you before you do one good one.” “One man's meat is another man's poison.” “You can't please everyone.” Yeah, those work too. I'm forty-four, have been doing comics professionally for over twenty years, had high-prestige clients, but I'm still learning. I'm not one to show exactly how to do comics or say how I do something is the only way. I don't even put clothes on people or make them other colors or genders unless it's necessary for the gag. My work is based more on ideas than craft. That doesn't mean yours should be. My stuff may be crude, but that doesn't mean I only can understand or appreciate things equally crude. I've centered on this style from trying other ways to figure out what's best suited for me. Other cartoonists might think everything I've said is a load of crap and I can live with that. My advice is to just take in as much as possible from everything you hear or say and use what you feel is best for you.
Bonus Tip #1: Don't Be a Cartoonist. You have a life of starvation and poverty ahead of you. There are enough of you already. I was bitten by the bug early on, but it's not too late for you.
Bonus Tip #2: Schulz doesn't have a "T" in it. Whether a classicist or iconoclast or intuitive, we can all agree Charles Schulz is one of the most influential cartoonists, some may say artists, of the twentieth century, yet most of the time I see his name misspelled. Enough already. You wouldn't get away with misspelling “apple” or “telephone.” It's somewhat understandable with so much lazy journalism, but there's no excuse for cartoonists to write “Schultz.” If you do, you should have your hands broken and be forbidden to attend any convention for life. Same goes for Winsor McCay and Jules Feiffer.
You can view Sam Henderson's work at: http://magicwhistle.com/