Yes, it looks like arse. Doesn't matter. Pay attention.
The ROYG Method
Roll d8+d12 for the monster type as normal.
Then, you have the illusion of choice. Roll either a d4, d8, d12 and d16 (or d20 and ignore results 17-20); or roll another 4d4. Consult the attractive (?) colour chart as required. The general principle here is that red is bad for the PCs, amber and yellow are progressively less bad, and green is nice. Strict rules of interpretation are not provided - the aim is to give the DM's brain something to riff on, rather than providing absolute set-in-stone laws of interpretation.
The d4 result (or d4:1) tells you the type of terrain in which the encounter occurs, depending on the 'host terrain' of the hex. If it's a mountain hex, as the above table is keyed for, red will mean extremely steep cliffs or scree, amber will mean a steep-sided valley with the monsters at the top, yellow will mean a shallow valley with monsters on the high ground, and green will mean favourable conditions (such as the PCs being on high ground in a shallow valley).
The d8 result (or d4:2) tells you the rough proximity of the enemy. Red meaning right there in plain sight (the distance will be greater on barren mountain terrain than in a jungle, obviously), amber in the distance, yellow the monsters have spotted the PCs' trail but not the PCs yet, and green the PCs have spotted the monsters' trail but not the monsters yet.
The d12 result (or d4:3) tells you what the monsters are up to. Red could mean hunting, on the warpath, etc. Amber could mean patrolling without active hostile intent (though that will change if the opportunity arises). Yellow might mean looking for something, foraging, etc.. Green, idling, or looking for somebody to talk to.
The d16 result (or d4:4) gives a complication. Here, the DM has even more leeway to use his imagination. It might be suggested that red means another monster happens along. Perhaps a green result means that the monsters are actually long dead and only their campsite or remains still exist.
So, for example, on my d8+d12 I got a 14. The result is a ranger(s).
What are these rangers up to? d4 result for terrain gives 3 - yellow. A low valley, with the PCs towards the bottom, with a few rocks here and there for cover. The d8 result for proximity gives a 7. Another yellow. The rangers are in the distance - just about visible, or potentially so. I would then roll for surprise, assuming the encounter distance is, say, d6x200 yards. The d12 result for task gives a 6. Amber. They're roaming around their territory, checking to see nobody is bothering the local wildlife - possibly acting on information that there is a group of hunters in the vicinity (who they might mistake the PCs for). The d16 result gives a 9. Red. A complication. Hmm..... Okay, there is a group of NPC hunters in the vicinity and they have spotted both the rangers and the PCs.