A professional voice recording needs three qualities: no background noise, no audible room, and consistent level. None of those require an expensive microphone.
Choose the right room
Pick the smallest, softest, quietest room you have, away from the street and away from plumbing. A carpeted bedroom with a full wardrobe beats a large office. Interior rooms beat rooms with large windows.
Absorb, do not soundproof
Stopping sound getting in requires mass and construction work. Stopping sound bouncing around requires soft material, which is cheap. Absorb the surfaces around and behind you: thick curtains, duvets, acoustic panels, a full bookshelf, a rug. Treat the wall you face first, then the wall behind you, then the ceiling above you.
Avoid tiny sealed boxes made of hard material. They sound boxy and get hot.
Hunt your noise floor
Record two minutes of silence and listen at high volume. Track down every sound. Common culprits are computer fans, hard drives, refrigerators through walls, dimmer switches buzzing through lighting, and the microphone itself if it is very cheap.
Move the computer out of the room if you can, use a long cable, and switch off anything mechanical while recording.
Equipment, in order of value
1. Treatment. The largest improvement per unit of money. 2. A microphone stand and pop filter that hold position reliably. 3. A clean audio interface or a good USB microphone. 4. Closed back headphones so you hear problems as they happen.
A well treated room with a mid priced microphone consistently beats a bare room with an expensive one.
Set up for repeatability
Mark where the stand goes, where you stand, and the settings you use. Clients often need pickups weeks later that must match the original session exactly.
Test properly
Record the same paragraph in several positions in the room and compare. Then send a sample to someone who records voice professionally and ask what they hear. You stop hearing your own room very quickly.
Maintain it
Check cables, replace foam that is degrading, and re-record your noise floor test every few months. Problems creep in slowly and are easiest to catch by comparison.