Rain barrels and gutters: my DIY setup and looking for tips

I've been thinking about setting up a rain barrel system to catch water from my gutters. Did some research, and it seems pretty straightforward - installing a diverter on the downspout, hooking it up to a barrel with a screen to keep out debris and mosquitoes, then adding an overflow hose. But um...I'm wondering if there's anything I'm missing or if anyone has found better ways to do this? Maybe something you learned the hard way, haha.