There is no need to get a kit, but if the kit contains what you want, go for it. The "kit" is someone's recommendation. It may be based on usability--give you what works well together, or it could be based on their preferences, or something else (such as kit is $5 less than buying individual pieces). Either way, if the contents/price is right for you, you win!
Example: compare this (last I checked, I think this deal was equivalent to getting a free case.)
to John D's recommendation (contents and prices). Add some carto's and a juice sampler, and you're pretty much matching John D's list, with backup battery and 2 different ways to feed the ejuice.
No need to go crazy to start either (that will come, sooner or later), just some setup that works without problems. Once you feel comfortable with that, you can contemplate where to go next. My starter was a basic 510 (came with 2 batteries), with a clearomizer (came with 3). I added another battery. My case was an old eyeglasses case. 2 flavors of ejuice. Was not ideal. Was not fancy. But it did give me a good starting point that worked! Each one was about the size of pen or Sharpie marker, and as such, was easy to carry, even without the eyeglass case. And today, as I've acquired more vaping gear, these are still part of my 'rotation': 510 with a carto currently in my shirt pocket. Lavatube with rebuildable atty (SS wick) alongside the mouse, and a few other pieces waiting their turn in my eGo case. That's where I've gone. Someone else I know started with 2 bottom feeders over a year ago, and is still happy with those. Another actually bought the over-priced 'kit' from the kiosk in the mall, and loves that.
If I were back at the beginning, an eGo twist kit, like has been described here, would probably been the best overall for me to start.
i definitely like that kit, so im a little broken up between the links provided earlier and this. the batteries on the kit are the real deal joyetech ego c twist right?
also, ive seen cartomizer tanks, looks like a cartomizer goes inside the tank? are they prone to leaking?
i dont think ive seen a cartomizer tank faq around but if anyone can link me to one that be greatly appreciated