When the time comes that you want to start initiating social activities, here are a few suggestions:
The best predictors of future relationships are proximity and frequency, in other words, the number of times one person gets physically close to another. Think about who you were friends with as a child, at school, college or university, or at work. Physical proximity usually plays a major role. You may or may not like another person who is proximal to you, but if you do like them it is extremely likely that you will develop a relationship. There are lots of other people you could like and develop relationships with, but without spending some time with them you will never know and do so.
Just as we have personal space (about one meter on average) we have proximal space. This space is the area covered by the average room in a home. If you are within this distance in relation to another, their perception is that you are “here”. If you are beyond this distance their perception is that you are “over there”.
The second part of this equation is frequency. It is largely a matter of probability, but the more time you spend with others, the more likely you are to discover if you have mutual ways, views and interests. If you encounter members of your new social circle on a regular basis, at least twice per month, you are very likely to develop friendships with them if the other factors are present.
This is why our default strategy when feeling socially isolated is “find a group and join it.” We instinctively know the two criteria, proximity and frequency, required to create new connections. The very fact that there is a group means the members will meet on some kind of regular basis. Unfortunately, this strategy does not always work because the groups agenda, or reason for being, is likely not just to meet new people, socialize and make friends. It is usually to play bridge, save the whales, win the cup or some other focus and efforts to simply socialize are not always welcomed. However you can use the same simple strategy that they do to achieve their ends to achieve yours, create social connectivity through proximity and frequency.
Keep in mind that people prefer structure (as do all primates) thus they prefer social events that take place in the context of an activity of some kind. The primary reason is that it takes the focus off of the participants and makes them less self-conscious. This is why things like games or sports are so popular.
By the same token, if you keep planning the same social activity then soon only those interested in that specific activity itself will show up anymore. Those who are interested primarily in the social aspect will soon drift away. Conversely, by varying the activities you guarantee that only those interested in socializing will continue to show up. The others will go join a bridge, tennis or hiking club or whatever one meets their interests.
Keep the barriers to entry low, including costs. The simpler the activity, the more people will be interested. If attendees regularly need such items as gym shoes, a tent or a knowledge of philosophy, then you are not going to have many takers on an ongoing basis. Also not everyone can afford to spend money on social activities four or more times per month. If you want to reduce this barrier to entry be sure to include plenty of things that have little or no cost such as walks or games.
Generally, keep the number of participants to any social activity to twelve or less. This is the optimal size for social situations. The reason for this is that once group sizes get larger than a dozen people, cliques form and some members begin to feel disconnected. Beyond twelve a group becomes a crowd, where one can still feel lonely. With groups smaller than twelve, people notice and take action if one of the members is not being included. Beyond this number, this behavior is less likely to occur.