Okay, then we mostly agree. Here are my tips for newbies (especially if you aren't sporting kevlar and a riot helmet) when entering into any situation, especially one that appears to be special or unique;
1) Before starting a fight, check your HP and use a First Aid Kit if you can spare one.
2) Check your 1st line armament. A couple semi-auto handguns, a high level melee weapon(s), and a large rifle seem to be universally accepted. Also acceptable is to equip a riot shield instead of one of the handguns or melee weapons. Consider putting first aid in your 2nd row; if it is accessable and you're taking lots of hits, it might save your life.
3) Equip your most damaging weapon(s); sometimes trouble appears and you don't have access to your inventory. Rest assured, if the situation turns out to be less than intimidating you can always switch and play with tools or more creative weaponry.
4) Carefully read your options. In non-combat situations consider putting some other items (tools, etc.) in your hands, then check your options to see if that makes any differene. Along the same lines, consider taking items/weapons out of your hands. But, be careful before disarming yourself in the presence of others; it is very rarely advisable (only a couple times to date, and both times the person(s) were minding their own business and not doing anything strange when I found them). Also keep in mind that some tools have offensive capability; I'll leave it to you to figure out which tools I'm referring to.
5) Once you start fighting, keep an eye on your HP and ammo. Cycle weapons if ammunition gets low. Use first aid if health gets low (if you die, it is gone anyway).
6) Use your best judgement when determining kill order: kill the large targets - they'll attack the following round, grouped targets - if you have a weapon that might strike and kill several in a single round, targets that are getting lower in the screen - indicating increasing initiative which might make them more dangerous if they attack and/or prevent you from switching weapons or running away.
6) Don't be too proud to run away, survive, and kick butt another day... if you can. Choosing when to engage the enemy (and when not to... to run) is as important, if not more important, than the weapons you bring to the fight.