Part of anti-capitalism is the rejection of neoliberal ideology where people are voluntarily pursuing achievement and performance as expressions of personal freedom. Byung Chul Han wrote about these concepts in books like "The Burnout Society", "Capitalism and the Death Drive", etc
In our supposedly free society, the social pressure to "do well" creates the burnout. People work hard because of an illusion of scarcity rather than the boss exploiting them.
There's a lot of 'don'ts' in my reply. I'll try to add some 'dos'. And I'll caveat this by saying we can only do so much under capitalism.
I would say: do not tally every expense. I realise many people may not have much money. And this won't work with selfish 'friends' who either do tally every expense or who will let you pay for things without ever contributing themselves (it's different if they can't afford it; I'm talking about those who can afford it but who take advantage of you).
That is, do not treat every interaction as a financial one. I know married couples who keep their money separate and make sure that what one spends, the other pays back. Wtaf? How do you have a loving relationship if you let money meditate every action and determine every decision? Okay, split the main bills. Whatever. But don't demand your spouse pay you back for what you 'lent' them at the restaurant.
It's similar with friends, etc. But this also means being respectful of people's circumstances. It means going places that people can afford. If that means going for a walk in a park and taking a flask, do that. Don't drag people to a Starbucks and expect them to spend $10 on a shit coffee and a mouthful of dry chocolate cake if they don't earn much.
That is, to be anti-capitalist means to reject bourgeois relations. Don't judge people because their clothes branded. Or because they don't otherwise dress like a mainstream celebrity. Don't turn your nose up because someone's house is sparsely furnished. Don't judge people for being houseless or homeless.
Treat the working class for what they are: the people who keep the world moving. Be kind to servers. Say hello and thank you to the cleaner. Treat them with the respect they deserve for being equally human.
It's not entirely possible to avoid bourgeois things. But it's possible to do less-bourgeois things. E.g. Preparing a picnic or cooking together is less bourgeois than going to a restaurant. If you travel with others, coach and a hostel or 3* star hotel is less-bourgeois than business and a 5* hotel. Locally, walking or catching a bus is less bourgeois than getting a taxi. These are just general ideas, though, and they're not always possible, especially the taxi thing.
Maybe it's a personal thing but I detest doing things 'to keep up appearances' because it almost always boils down to spending money – i.e. consuming, buying commodities – for the sake of it. My overall advice is to resist that impulse. Reject it when others suggest it. And don't impose it on others.
Like, if you do something for you birthday, don't price out people who would like to join you. This also means thinking of accessibility and inclusion. I know people who will go to the place they want to go (even for a working lunch) but which isn't wheelchair accessible, for example, even though there's a friend in the group with a wheelchair. Or if your friend doesn't like crowds or brightly lit places, don't go somewhere busy and bright. FUCK people who do that.
Such exclusionary decisions are one of the ways that individualism manifests and I hate it. I hate it most when it's done so that someone can say they went to the posh place and take photos-with-no-artistic-merit of their food. They're earning their middle class credentials. Don't do that. Think 'inclusion'.
Don't get taken advantage of, but be selfless to the extent possible. I suppose part of this means doing things that don't cost money or (because that's very difficult) keeping the costs low, so it's more about socialising than spending money.
Isn't socializing inherently anti-individualistic? My relationships are mutually beneficial. At the very least we enjoy each others' company. We help each other out of care for one another. Over the years we have positive effects on each other that grow our love for our fellow humans. Maybe it's just the kind of people I want to be friends with, or maybe I've misunderstood your question.
That's it. Even just going to a cafe with people. It doesn't take long before someone says, I'll get the cutlery, do you want any ketchup while I'm at the stand. And another person grabs a tray to carry the drinks to the table. While another is lagging behind because they held the door for someone with a pram – but don't worry, someone else brought them a chair over to make sure they have a seat when they catch up.
I don't know any particular books on this so I don't know what I can suggest.
I think it is good to help people out and generally be polite, forgive small transgressions, but firmly correct them when they revert to language that disrespects minorities.