Hmmm... well, it's winter and you're likely using some kind of desiccating heat source, so the air prolly has low humidity - that increases static activity. Maybe think about using an air humidifier in the area you build in. Here on the coast, where "dry" air is >50% humidity, there is far less static and I haven't fried a component ever.
I'd build on the floor, myself, and I'd wipe the portion I use with a fabric softener sheet if I had one handy (they have a chemical that reduces static cling in laundry).
Work barefoot, nude if you can (quit giggling, you lot - clothes harbour a lot of static electricity) - if not, wear cotton, never wool, leather... or PVC
. Good that you have a bracelet - you're actually the worst source of static.
Yeah, get the PSU grounded (plugged in, switched off, and strapped). This is where the debate has been amongst geeks - no definitive answer as to whether or not this is better. Just never touch the electronic components without first touching a ground, like the metal frame of the computer (which should be, at all times, sitting firmly on the floor, not on cardboard/plastic/carpet/etc). The strap should make this a redundant precaution, but hey, it can't hurt.
Your chances of frying anything are quite small - the above is overkill - but it's heartache when it happens and you do live in a relatively static-prone environment, so best to err on the side of caution.