In traditional studios, you have separate rooms for tracking and mixing, and each has very different acoustical requirements. Main rooms typically have minimal absorption and are designed to be reverberant, with movable gobos (absorbent panels) for spot treatment where needed. Control rooms, OTOH, need to be tight across all frequencies so that you're hearing the tracking room and not the mixing room.
Unfortunately, we bedroom producers and garage recordists don't usually have that luxury. We track instruments and vocals, and mix and master all in the same room. Those rooms are often too small, badly-shaped and overly resonant. You really don't want to hear those rooms at all in your recordings, because they have nothing pleasant to add.
The solution: make the room as dead as possible and rely on reverberation plugins to restore some life. It can be expensive to fully treat a room, so you may want to concentrate on a small part of the room. Start with the mix position, putting as much absorption as you can around that area so that whatever reverb you're hearing while mixing is in the recording, not being added as you mix.
Second most important is a dry space for recording vocals. Those microphone shields are not a solution. A finishing touch perhaps, but they shouldn't be your primary strategy. For the price of one of those, you can buy enough rigid fiberglass to construct an entire vocal booth that covers more than just the backside of the mike. You'll be amazed at the difference that'll make!
If you're tight on space and/or money, you can kill both of those birds with one solution: movable absorbers that can be place next to your desk while mixing, or placed around the singer or guitar amp while recording.