How to have better conversations?

whether its with my closest friend or someone from work, i sometimes have trouble keeping up a conversation. I'm good at talking about what were doing, or something were doing later, or something we did, or about something that's going on in my life or their life, but i have trouble just chatting from topic to topic and just talking mindlessly. i'll find myself talking for just a few moments about one thing, but it usually never flows into anything else. i guess im just not a talkative person, or im just too shy, but its getting to the point where i feel like my friends aren't as close to me as they should be, or i'll find myself having an awkward silence with someone at work. and i feel like it just makes people think im an asshole who doesn't like talking to them, when i really do want to. Does anyone have any suggestions or good websites? Thank you so much.