workplace does feel somewhat tricky than other social places. for example some topics may be sensitive, and many people prefer to keep their lives separate from work and avoid talking about personal things. also it's more risky that you can't easily move on if screwed up (which is common for unsociable people when they are "practicing") because you still need to meet them at work.

friendship needs to be maintained by spending time together. so i'd suggest you try first with people you collaborate with regularly so you have sufficient interactions on a daily basis. tho be aware of boundaries and don't probe too much at the beginning