The battery needs to be fully charged. Fully charged it's good to very low temps (Well over 30 below) Fully discharged more like 32+
If you have power either a battery tender (Very low power smart charger) or plug it in and let the converter (if it's a 3-stage) do the job)
IF you choose to remove it to say your basement
First... Spray or paint the positive leads RED (Optional black on the negative) if they are not already.
Take pictures (Multiple)
When disconnecting.. If a terminal has more than one wire (Other than jumpers) Tie them together.
Wrap the positive wires with plastic wrap to insulat them (no need on negative)
Disconnect negative first
Take battery inside and set on a piece of scrap wood or in a plastic "Tub"
MYTH: if you set battery on cement it will ruin the battery.
Fact: If you set the battery on Cement, or any other flooring it MIGHT (no guarantee) ruin the floor.. But if you set it on scrap wood.. Well that's kind of low cost :) (I mean it's scrap already).
And again I'd suggest a battery minder/tender (Two brands of same type of device)