I used to do this a lot, less so nowadays, so I understand how you are feeling op. You have got this! Most of it, you probably already know, but just in case:
Give yourself plenty of time to get ready and travel, so you are not flustered when you arrive and if you are hosting in a social sense; get there before the other guests. Wear something comfortable that makes you feel good. Drink enough to relax you but not too much!
Be yourself. Breathe. Be calm. Don’t put too much pressure on yourself - people are expecting to meet an ordinary woman - you are more than. good enough! 😀Don’t go in there with any expectation of being a sparkling hostess (I get you only used that phrase to liven up thread title!) ; but nonetheless just be content with being quietly interested in others.
Introduce yourself clearly. Listen. Slow your speech down. Smile. Stand up straight with open body posture. Remember names (use a mnemonic). Ask questions. Listen to the answers.
Don’t be distracted while talking to people, make sure your entire attention is on them. Don’t t be afraid to pause to think briefly before you respond to something they say (that is far preferable to someone who is talking over people or who is rushing to get their reply in out of nervousness or being too eager).
Don’t forget to use non verbal cues that you are listening eg nodding, smiling, raising an eyebrow or whatever, which makes the other person feel encouraged and heard.
Say something positive about the ‘actual’ hosts to other guests such as “isn’t this a marvellous spread set out by x and y” (along those lines - you can think of something better!).
I’d also be sure to introduce yourself in your own right rather than “hello I am wife of” and avoid using “how do you know my husband?” and “what do you do?” as that could come across as a bit superior without meaning to be! Better to use collective phrasing such as “did you get rained on as well?” (again, think of something better than that!) .
Presumably if the clients are mainly blokes then their wives and partners will be feeling as intimidated as you about not knowing many people, so focus on making them feel at ease, rather than on your own discomfort, and you will enjoy it more.
Also your mindset should be “I am one of a small group helping the team make this evening a success” rather than “all the responsibility is on me/what will they think of me/oh god what if I can’t think of anything to say?”. The truth is that, generally speaking, people are more interested in themselves than others.
Don’t allow yourself to panic or feel uncomfortable if you find yourself alone temporarily, just breathe and stand there calmly, or move slowly and re-group. Don’t rush. Maybe look for someone who is looking lost and ask them “do you know many people here?” Or failing that, ask the other hosts if you can hand around or top up drinks.
Finally, tell your dh you are feeling nervous and arrange to have a mutual code word or sign that will indicate to him that you need support. Tell him you hope not to use it, but you will feel better knowing it’s in place! (If he is anything like my extrovert dh though, he happily agrees to this, and then forgets! 😃)
Hope it all goes well op and that the evening is not too gruesome for you! :)
Good luck! 🍀🍀🍀