If it's your first big trip alone, or first time without your family, planning and making bookings on your own can be tough. How do you know when you're getting a good deal or what happens if my flights change? Usually the best first step is to look around and get a good idea as to where you want to go, make sure to not just stick to one website and check out different airlines that may be headed to the same place as sometimes you can get a get deal for pretty much the same flight. When I was looking for flights to Reykjavik I ended up finding two of the exact same flight on different websites, I paid half of what was on the airline site by booking through an affiliate instead of directly through the airline for the same flight.
And so, you find a great deal online but you aren't sure whether to commit or not, if that is the case a travel agent is the best place to book for you. A common misconception is that you have to pay tons to get your booking done, when in fact there are tons of free travel agencies to choose from. You can bring in flights you found online, just take note of the flight number online, and they can find them in the system and even compare to see if there are other flights that work for your needs. If your flights change or they need to extend a layover etc, the agent will call you directly to inform you of the changes to make sure you're on the same page and are okay with the changes being made. I've had some great experiences when it comes to travel agents, including a flight switch that landed me with a free week in Fiji, which I otherwise would never have been able to afford.
I still think that after getting used to booking you may no longer need a travel agent which is totally fine. I still from time to time will book with an agent, usually when I'm traveling with someone else who isn't a huge traveler to make sure that we're covered by the agency for flight related changes. When booking with an agent, a thing to consider is that if one night you see a great deal there is no guarantee it will still be there if you head there the next day. Prices fluctuate like crazy and you don't want to wait if you see an amazing deal and that is when I'd recommend booking ASAP online to save you some cash.