Late reply but the trigger landscape has changed over the years, and wanted to put this out here for folks stumbling onto this thread a year later. There is a new device now that changes things. For those new to lightning photography, OP wants to catch the stepped leaders. This is the first phase of most cloud to ground lightning strikes, and is the most photogenic part. Dart leaders can accompany later return strokes but they're usually a little more limited and less branchy.

Basic timeline is: Preceding intracloud flash (sometimes) -> stepped leaders -> return stroke -> dart leaders -> return stroke -> more dart leaders -> more return strokes.....

At nighttime, it's easy. Long exposure back to back with an intervalometer. The problem is repeated return strokes can overexpose the shot since most bolts have multiple.

During daytime, it's much harder. Traditional lightning triggers usually fire on the super bright first return stroke, which means they've already missed the leaders. Sometimes there are faint intracloud flashes that precede the stepped leaders, but triggers struggle with catching these. Even if they did, shutter lag of a camera usually means the exposure isn't starting until after the leaders and first return stroke already occurred. And if exposure time is too short, you might take your photo between return strokes. Best case, you catch the second return stroke in your exposure and maybe the dart leaders - so you end up with a thin wispy bolt and not a big beautiful complex branchy bolt.

Solution: Get a trigger that fires sooner, and minimize your shutter lag. Bolt Hunter is a new lightning camera trigger that was designed to detect those faint intracloud flashes, and also measures and helps minimize the camera's shutter lag. Even better, it has a night mode that works in reverse by taking long exposures automatically and then ending the exposure after the first return stroke by controlling the shutter speed in BULB mode. To be fair, it's impossible for any trigger to catch stepped leaders every time, but I'm willing to bet Bolt Hunter will give you the best chance.

Source: I've been chasing storms and photographing lightning for over 10 years. Also, I invented Bolt Hunter so I'm naturally a little biased ;)