The fundamentals are the same on all modes, get your hit counter up as high as possible with hypers for the first half of the stage, then fill your hyper gauge to max and never use it again. Power just has a lot of advantages doing this! Also note that certain enemies have a higher point value than others, and these are typically at the start of the stage, so including them will give you a much higher score. Dropping your chain after the big tanks in stage 1, for example, will give you basically nothing even if you do the rest perfectly.
If you just want to hit the second extend then I'd aim to chain stage one (the only tricky link is after the last tank in the opening section), and chain stage 2 with the tank trick. Do this and you'll either hit the extend or be close enough you don't need to worry. The tank trick means point blanking the the laser pods that the stage 2 hidden mid-boss drops on his final pattern with your hyper laser, as these will boost your counter to crazy numbers in a matter of seconds.
The problem is keeping it alive long enough to do that without dropping your chain, you'll want to have a hyper ready as you enter the fight and activate it once it starts doing its burst patterns from the main cannon - this way you can shoot down its shots to keep your chain alive while not hurting the tank too much.
http://www.youtube.com/watch?v=Gd9Z6tF6T7w (Power mode, but it's the same thing)
Also, to clean up what I said above (and in other threads I believe): I know why I was getting confused about the extra boss requirements! Missing a bee means revealing it and letting it go off the screen, if you never even reveal it in the first place it's not a problem and will not stop additional bosses appearing (though obviously you should be aiming to grab them).