digitalforce: I usually miss when I attacked (A key) and then sometime I kill stuff when I cast a flame arrow or something.
At low levels, Bless is very useful spell. It increases your chance to hit. You might also want to choose type of weapon for each char, and invest some skill points there to increase chance to hit and get other bonuses. You can always attack by clicking on mob (which makes it much easier to focus down one particular mob/runner). One of fountains in New Sorpigal also boosts your Might by 10, which can also help you before going to dungeon.
digitalforce: Overall, even the first abandoned temple quest, I get overwhelmed by 6+ enemies!
I would say that Goblinwatch is more like beginners' dungeon. Make sure you clear New Sorpigal first (it has around 14 chests with valuables and 1 hidden chest which looks like rock). Don't stand in melee range of mobs for too long when you are low level. Unload all you can on Goblin Kings, King/Queen Cobras, Giant Rats and Huge Spiders before they come even close.
You could also visit Castle Ironfist and mess around there a bit, teaching everyone to use bows and such. Misty Islands is another low-level friendly area - you can reach it by boat either from New Sorpigal or Castle Ironfist.
In general you will want to avoid getting stuck amidst 6+ mobs at low levels... Until you get some real nukes. Abandoned Temple has infamous Cobra Pit, don't rush there, use Wizard Eye spell and slowly approach it, slowly turn around - if done right, only 2-3 cobras will come to you at a time. Remember, you can always retreat and shoot some mobs from afar.