Social capital is obtained by building goodwill. This is the simplest way to describe how someone can build or obtain social capital. Social capital can be observed at the level of the individual, group or community. At the individual level social capital is best understood as resources made available or accessed through social relationships.
For an individual, social capital primarily relates to the people they know, how well they know them, the quality of these relationships, the degree of goodwill (or reciprocity), and a range of factors relating to reputation.
So, to obtain social capital you need to be social, giving, respectful, and trustworthy. You need to get to know people and strengthen relationships with people you already know. You need to help people, give without expectation of favours being returned, you need to trust and be trustworthy, you need to be honourable to build a positive reputation.
Since social capital from the individual perspective relates to access to resources it helps to know people who possess diverse and valuable resources. Knowing hundreds of people who all have much the same resources (knowledge, tools, assets, etc) is not as valuable as knowing people with diverse resources, for example different knowledge, networks, tools, assets, etc. It’s also good to know people who are different to you, who know different types of people and have different knowledge, skills, etc.
Above all, obtaining social capital is about being a good person – a global citizen. Give and you shall receive.