Quick question about instructions for tuning fuel trims for 2g

[Quicksilvergsx]

I'm trying to dial in my low throttle fuel trims. For 2Gs it says:

2g: 2g's only have 2 fuel trims, a long term fuel trim (LTFT) and a short term fuel trim (STFT). The STFT varies with the O2 sensor, an the LTFT goes for every rpm range. Since the STFT directly effects the LTFT, then you can just add the two together, and tune from there. For example, if the LTFT is +20%, and the STFT is -5%, you are at approximately +15%.

at idle my ltft is at -9 and my stft stays close to 0. Does this mean I need to lean it out about 3% on the safc? I am confused as to which numbers you use exactly. Or is it fine if the stft is at 0 even though the ltft is at -9? Also a -9 ltft means that most of the time I am running rich correct?