After removing the glass, I'd suggest scraping off any remaining black adhesive off of the iPad's frame. Get every speck. This may be time consuming if you have lost glass integrity and have sticky, splintered shards around the edge of the frame, but you need the frame completely clean of adhesive before you put the new front panel down or else it won't lay correctly in the frame.
Definitely not for the weak of heart, especially if your screen lost all its integrity when it shattered. You'll be scraping glass splinters off the frame for an hour. Tip: Make sure to scrape off all the black adhesive from the frame of the iPad (and I mean every speck) before putting the new screen down. I apparently missed a spot, and I can't get the screen to seat perfectly within the frame (but close enough; I'm not going back in there). Also, I didn't have much luck with the microwavable tube for softening the adhesive, but I was fortunate to have a heat gun that helped quite a bit.