Flanking is a key during combat, I've found. I had to crack open the Player's Handbook to figure out why my crossbow bolts and arrows were never hitting anything. If you try to shoot over the heads of your fellows, the moster is considered under partial cover to ranged attacks! In other words, if my druid is standing between my bard and the frog, then the frog's AC is improved by the cover provided by the druid and gets a better chance of being missed by the bard's arrow. So now I move my archers to the side to get them clear shots, and they hit a lot more often!
This is what comes from not actually playing PnP recently, and not reading every word of the manuel!
But I went to the moat house with five level 1 characters and no NPCs. I had to do a lot of healing, resting, healing, resting, but I made it out.
Spoiler (highlight to read):
Once you clear out the spider in the small tower in the south side of the moat house courtyard, you can rest there without the threat of random monsters! 