Mix and match phrases! Intro/build of track B into chorus of A so next tune’s is next beat. If it’s a long intro, cue it up halfway through to avoid the ‘boring parts’ or use those boring parts (hats, vocal scratch, new synth) in song A to change it up a bit/ 
I actually found that with a Midi Fighter or anything of the sort you can make the ‘boring parts’ into some funky remix sites.
Play other songs underlying with a beat to fill the empty noise. Use the bass from track and the highs from another.
always transition in the 4 beats before the drop very simple way to keep people on there toes… do some random mashups, have fun, and u can also transition on some breakdowns if they go together well..!!!
Just go with the flow u dont always have to wait till the first/last 16/32 beats to transition mix it up man!!! thats why they call it mixing
27wonka
echo freeze is your friend…
no one mentioned TALK ON THE MIC…if you don’t use a mic you can always simultaneously cue jump to an instrumental loop in the old song (usually in the outro) and start the new song on the vocal…this kinda minimizes the unessential breakdowns in my sets…but sometimes breakdowns are a great time to talk on the mic…cut the bass outta them, or turn the volume down to 80% so when you bring it back on the drop it’ll have that EXTRA energy at 100% again.
Also, having a few looped samples ready to go never hurts. Could be drums or anything else that will help keep the rhythm going and the energy up. I have a few crowd chanting/clapping sort of samples I drop on certain breaks that lack the energy to make it on their own.
The breaks you describe at the beginning and end are for mixing in records before we had cue points and loops. They would often do long intros and outros in these remixes so DJ’s had time to get it going correctly.
Check out the YouTube pioneer dj sounds show , laidback Luke’s set for power mixing.
also an important question:
is the crowd dancing? if so, it might just be you feeling that way.
I don;t like too many breaks either.
I find it tires the crowd more than giving them a break.
Irritates me when i am grooving and then break…groove…break…groove…break.
I tend to put Cue Points around my breaks and play em if I want…else I skip past and keep the pressure.
beatslicer take a loop from the intro beat while dry/wet is 0 then when you get to the long break (That I also am not so fund of) add some wet to your Slicer and you got an underlying beat to the not so boring break now. and you can use that Slice/Rool/loop to make some extra buildup or exsitment.
Think it loop rool, in VDJ. Some of Pioneer mixers also have this rool.
This is what you use Ableton Live for. Personal edits can be as simple as removing the break.
or set cue points…