Here is my response to a letter from a college-age LII asking for tips about how to find an ESE dual. I thought the topic might be interesting to other readers.
Finding a particular type over the Internet is problematic unless you happen to be on a Russian language dating site that is based on socionics. On other sites expect that if you pick out 10 people you're interested in and think may be ESEs, only 2 of them will turn out to be ESE. Part of the difficulty is that everyone is trying to be positive and present qualities that others will find attractive, and it will be easy to mistake people's self-descriptions for possible ESEs.
My general advice is to not look for a particular type, but to focus on being yourself and doing things with sincerity and interest, and in general to follow standard advice for finding and developing new relationships. Put yourself in a position where a lot of new people will be crossing your path so that the odds are in your favor, and focus on expressing your personal qualities, talents, and interests so that a potentially compatible person will recognize you as such. Finding and keeping a dual is probably more about personal development than it is about knowing what to look for in others.
It's important to learn to take responsibility for your gender and type role when getting to know other people. In other words, to learn to do basic "man" things in the initial stages of the relationship, and to do the types of things that a dual type would be expecting. For instance, ESEs probably won't be expecting you to be super active in getting to know them initially. They'll enjoy the challenge of opening you up, discovering your interests and views, and involving you in stimulating and fun activities. At the same time, they'll be expecting you to be firm and confident and to express a clear interest in them in a manly sort of way.