Cant really give you an accurate suggestion since I tend to be a lone wolf however there are some things which helped me to join situational social circles (those social circle which involve people going after the same goal compared to social circle based on "friendship").
So the first suggestion is not to create any problem regarding their habits, if they eat mc donald after a meeting dont bother them with your vegetarian requests to go somewhere else, dont be a hassle to have around or they will simply not involve you rather than change for you.
Second suggestion is handle with care the women in the circle which means dont go after the girl some of them like before you become a regular in such circle, also avoid any tenstion with the girls, we all know that if a girl dislike someone so will her friends and if all the girls dislike someone the guys would rather drop you than them, especially nowadays.
Third suggestion is to somehow add something to the group, provide some benefit in involving you, if you have a car and some of them usually go with bus, give them a lift, when you are necessary you can afford of being much less diplomatic, those guys you give a lift before and after the match are your walking invitation.