I am starting to work on open source projects and make contributions on some well known projects. I wanted to know how well this is for me professionally and how can you come about creating connections with other people on open source project hosting sites such as github etc.
As in every other place: talk to people and communicate about the matters at hand.
Usually FLOSS is a meritocracy... so to become a member means to become engaged consistently and positively and constructively and people will start to remember you - especially if you tackle the nasty bugs - that usually is valued more than to just go there to push your shiny super-duper features you deem necessary to scratch your own itch.
So a good way to start is to go to the issue trackers. Often you may find issues marked as "good first issue" etc. Start with those to familiarize yourself with the project, how things are handled, and the code base. Then move on to more complicated issues which interest you.
Also make use of the other communication channels a project might have, be that IRC, discord, mailing lists or whatever. Initially listen more than talk yourself. That way you will learn how things are expected to be handled. Every community is different. Avoid the toxic ones.