The simple thing I tell people to do who are uncomfortable with more complex negotiation is, just before you're about to accept the offer, just ask if they can

The simple thing I tell people to do who are uncomfortable with more complex negotiation is, just before you're about to accept the offer, just ask if they can increase it any. Just straight up say "Is there any room to increase this offer?" If they say no, just accept it. If not, let them increase it, then accept that increased offer. I've gotten an increase at a significant majority of companies doing this and it's essentially zero cost.