On your liteon, scan at 8x speed.
Your results should remain under PI: 280 & PIF: 4 for a good burn, although you can usually ignore small spikes that exceed these limits (kprobe has been known to throw in a few high spikes for no significant reason).
It's the mountains that you have to watch out for.
An excellent quality disc will have PI <25 (most <10) & PIF <2 (most <1)
A good quality disc will have PI <50 & PIF <4 (all under 4)
A poor quality disc will have PI 50-280 & PIF <4 (occasional spike over 4)
A coaster will have PI exceeding 280 and/or PIF consistently over 4 or mountains peaks >5.
As to what speed should you burn at ... if you don't know, start at the rated speed of the media.
Although for CD's I generally just burn at 24x, the time difference being the time it takes for me to get up, wander to the fridge & grab something to drink.
Similarly for DVD's. The difference between 12x & 16x is negligible, however, the PI/PIF often goes mental for in the 16x zone during burns, so it's really not worth the 30s difference to chance a coaster.
Once you get a little more advanced, you can start over-speeding low-speed media with acceptable results, sometimes with better results than 16x rated media