Very briefly, I have to go in a minute.
Straight on, i.e., 90 degrees up and down waves, you risk going down a wave and "dipping" your bow in the next wave.
"Surfing down" a wave, i.e., riding DOWN the face at the same speed of the wave, you risk the same as above.
"Surfing up" a wave, i.e., riding UP the face at the same speed of the wave, you risk the wave behind you catching up and crashing over your transom.
Going parallel to the waves, you risk rolling the boat into a capsize or throwing crew overboard.
The above mostly apply to fairly rough conditions. You want to take the waves at a 45 degree angle so you distribute the rolling motion over both the boat's axes. It may not feel right, but "trust me,"
it is the best way. This applies to going "up current" and "down current." Think zig-zagging.
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I have a page from a Coast Guard manual with pictures of everything above. I'll try to remember to scan and post it later today.
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Shifting the weight aft, drive up, and trying to "glide" through the waves (letting the flat part of the hull behind the V-bow absorb the waves) puts HUGE stress on the superstructure of the hull. Try to use as much of the bow as possible to safely cut through the water.
Hope that explains things a bit better.