Updated: Mar 1
When you're in the tavern of a major city it almost always has patrons inside willing to chat over an ale. You're looking to interact with someone, but not quite sure how. Use your environment! Lean back in that chair and fall onto someone who's standing nearby. Trip as you walk down the stairs causing somewhat of a ruckus. If there is a player bartender on that day, buy the person a drink and have the bartender deliver it. Send a drink down bar top towards the person you're emoting. It's little things like these that you see in the real world, so incorporate them into your roleplaying.
A lot of people have these very same problems or inner dialog in their heads. New roleplayers, experienced roleplayers, casual roleplayers, so don't feel bad or out of place. Sometimes you're feeling confident and you're the life of the party. Other times you're feeling less confident. There a few things we can consistently do to help break the ice or help you find interaction.
We all scroll over characters to glance at their name and other basic information. Trying to gather bits of information that we can use for a starter. What seems to work for me is just simply whispering the person and seeing if they're AFK or not. If I get a reply, I ask if they'd like to roleplay. Simple. It works 100% of the time because if they don't want interaction they just tell you in private messages.
Another great way to find common ground when looking for a conversation starter, looking at someones at a glance when you click on them. These little circles pack a bunch of information, and your character would have noticed these things first. They range from Auras, clothes, equipment, mounts, personality traits, only limited to one's imagination. These things can help start a conversation and also keep one going, depending on the flow of the conversation.
You see companions pets and hunter pets strolling alongside their friends. Try using this method as well as it's another starting point. Hunters can move their pets around, so it's even easier for them to begin interaction. I've often used my pet on my hunter for this very subject. It'll take building a personality for your pet, but it's easier to interact with a pet and talk than it is to continue to hum or chat with yourself.
Overall the best way for me has been through private messages, but I myself struggle with roleplaying confidence. Just remember, if they don't feel like roleplaying then it's their loss. Hundreds of other people are eager and waiting for someone to interact with them. So, next time you're strolling through the streets of your city and you see someone standing alone. Send a private message. Walk up and interact. Just don't feel alone in being shy or scared to act at times. I've roleplayed for 10 years, and I still have these feelings. Be confident, others want to meet you!