electro house, dirty electro mostly.

I'm doing the straight warping, and I'm trying to mix the tunes by ear, that is by playing them straight on the beat rather than having ableton do the beat counting. works pretty well except I can't listen to the cued song before sending it into the main mix, so my mix will be slightly off in some cases.

quote_"Warp setting should be Complex"

The only time that I'd ever recommend using the Complex warp mode is if you plan on straying far from the tunes original tempo and still really want to preserve the original pitch.
I recommend Always using repitch mode as it's the only one that won't introduce audible artifacts. If key and pitch are an issue then experiment with Beats or Complex.
Beats mode CAN sound ok if the track dosn't have many sustained sounds but otherwise it will give that wobbley sound. Ecspecially on bass lines. But in general Beats mode actually preserves transients and punch.
To me, Complex mode sounds really similar to an mp3. It's got this metallic sound and almost all punch and transients are lost when using it.

For warping.
Adjust 1st warp marker to 1st beat.
Then go 4 to 8 bars into the track and adjust the next downbeat warp marker WITHOUT double clicking on it to turn it yellow. Adjusting it AS IS will shift all of the rest of the beats in the track appropriately.
Jump to the middle of the track and see if the rest of the downbeats line up. If not you may have to repeat the process.
In general this method works perfectly, ecspecially with 4 on the floor stuff where you just adjust the 1 or 2 warp markers and then you're done.
But you will always have the problematic tracks where you have to manually move every warpmarker every 4 or 8 bars through out the entire track.