If it sits for more than 3 weeks at a time, I would consider a Battery Tender. If it gets regular use you probably don't need one.
+1 on the tender. About all you need. If it's a daily commuter for you your probably good to go. But if your commute is like 5 min each way...well getting a tender and keeping it on when not riding will for sure extend your battery life.
I see your in Cali so your not snowbound like us snowbirds out east for 5-6 months at a time but if it sits for a extended period plug it in.
I got a Schmacher at Advanced Auto for under $30. remember its a "Battery TENDER" not a "Battery CHARGER" your looking for (very important).