Buy the tools of the trade: pens, pencils, erasers, Bristol board, correction fluid, a light box, markers, watercolor paint, brushes, shading screens, a drawing desk, a scanner, and graphics software like Photoshop. Not all artists use all tools; more modern comic strip artists using computers don't usually use shading screens or paint for shading, for instance.
Keep a file full of magazine clippings and photos of people, places, animals and items that you may need as a reference if you need to draw them.
Doodle in order to develop a drawing style that suits you; the more unique, the better.
Practice drawing cartoon lettering by studying other comic strips.
Use your imagination to create characters and settings that are unique and will make your strip stand out from the pack. Draw from real life, but put your own twist on what you observe.
Focus on writing. Even if the strip looks great, no one will care if it's not funny. Successful strips like Dilbert don't feature great drawing but rather focus on strong writing and unique characters.
Think big. Generate a ton of ideas for story lines even before you begin drawing, because a daily strip requires over 300 gags a year.
Carry a pen and paper with you at all times to jot down ideas that strike you as funny.
Experiment with different types of pens to find the thickness of stroke that works best for your drawings.
Set aside time to write and draw every day. It's the best way to hone your skills.
If you plan on presenting your comic strip on the Internet, create three of four weeks' worth of strips before you start publishing them so that you create a buffer in case you aren't able to draw a strip on some days. If you are planning on submitting your strip to a syndicate for publication in a newspaper, make sure your product is polished, and write to the syndicate to get guidelines for submissions.