For many voice-over artists, especially new ones, dealing with unwanted sound reflections off of walls and surfaces, as well as outside noise, is a common challenge. You can have an expensive microphone, but if you're not in a good recording environment, your voice-overs are going to suffer. It's sad to see so many new/unaware voice-over folks having their auditions or work rejected not necessarily because of how they voiced the copy, but because of negative sound related issues. You don't have to build an exceptional recording studio, but get into a space where you're not going to have your voice-overs sound like they were recorded in an echoing cave or tiled bathroom floor. You Tube videos are full of awful audio; hum, hiss, a way off mike voice, distorted audio, "cheap microphone sound" with lots of sibilance-you name it.
Foam, sound blankets, and baffles are just some things that can be used to improve the sound quality of your voice-overs. Do some research on Google about this or go to You Tube and do a search about setting up a solid recording space before going out and spending a lot of money. And don't forget that large walk in closet that you might have could be a very good option to record in! You'd be amazed at some of the adequate, but not eye appealing recording spaces, voice actors use at home. Remember, the people who are hiring you to record don't see your recording space. They just want good, clean audio that adds value to their production. And check with headphones on to make sure your computer fan isn't heard in the background of your recording. If it IS, create some space between your laptop and the microphone.