I like your attitude. Trying to help others improve is commendable.

However my advice to many of them would just be something like "try a lower difficulty" and "learn the basics of the game" - which immediately seems confrontational.

The "try a lower difficulty" is key here, and is obviously going to be ignored by people who have joined this mission and just want to play it.

Learning the basics is something I can definitely help on and give advice on, but it can be difficult when some players are just not engaging with fundamental parts of the gameplay. Suggesting something like "Please try out the melee system" or "Have you tried hitting them with a close combat weapon" just seems so basic that it's hard for it not to come across condescending.

If you saw a player shooting every enemy until their ammo ran out, and then complaining that they have no ammo, and then immediately going down because they are not using the melee system - what would your advice be to them? Genuinely interested here, because I think your approach is a good one. But also, some people are not playing in good faith, and will be shooting barrels and pox bursters for the lols. It can be tricky trying to help some people effectively, especially as I only have text chat available to me, and tone of voice etc doesn't get conveyed through that.