OK, SAF earplugs might be super happening for reducing volume, but it also cuts out a lot of frequencies essential for hearing yourself properly. Putting 1 earplug in one ear isn't a very clever idea either, cos you are going to lose hearing in one ear real fast, and I can imagine that it will be quite disorienting if you have serious hearing loss in only one ear.
the best alternative is to purchase a pair of flat frequency attenuation earplugs, which reduce overall levels, but preserve a wider range of frequencies than regular earplugs - basically you hear more or less the same as you would without earplugs, but just a whole lot more quieter. They also attenuate some of the dangerous high frequencies, but the downside is that you also lose a little bit of bass response. but definitely a much better option than just regular earplugs or SAF earplugs. I strongly recommend the Etymotic ER-20 (
http://www.etymotic.com/ephp/er20.aspx). I've been using them for a few years and they've been fantastic... really very good earplugs! I don't just wear them for jamming, I also wear them at gigs, even on the odd occasion I go clubbing (haha).Ya I know very geeky but I value my hearing!
Oh yeah, guitarists if you want to hear yourselves better, take a few steps away from your amp, and angle the amp towards your ears. Makes a whole world of difference, believe me. Please don't wear only one earplug!