what i usually do when practicing emergencies is, once the power is gone, trim the plane all the way down. This way i can forget about keeping the A/S and concentrate on other things. in the 152 this works pretty well as it keeps recommended A/S for you.
IMPORTANT: Dont forget, there is a big difference in your glide distance & rate of descent with some engine power (practice) and no engine power (real thing). Dont think, just because you made this far during practice, that you can make it that far in the real thing. this is most dangerous when on downwind to an emergency field. You'd like to think that last time you went this far out too(practice), but when the real thing happens you have to cut it a little shorter (the base leg).
This is also important. When picking a field to land, it is often very hard to judge height. Because you will always suffer from the "Runway Width Illusion". The thing that helps me is to look at objects on the ground and compare them to the field. A tree usually is the best thing. I failed my first stage check because i didn't consider that. The other 2 stages was just perfect because i knew what to look for.
Hope this helps.