Do this. Big 3 for sure, and I believe a voltage meter is super important. Watch your voltage the first few times you are really turning it up. If you start to dip below your battery's resting voltage, turn it down a little and see where you are at. If you are getting that low, come back here and ask questions.
This all day. Most of the times the noobs only ask what's the best (insert wattage number) amp they can get, and people only answer their question and don't give any more info. Noobs don't know to ask the other things like electrical requirements and so forth most of the time, so I think that's a fault of the members here.