Cover all reflective surfaces. Draw curtains and pin sheets over tiles and mirrors. Glass and tile has a smooth, surface that reflects sound as well as light. Where glass is used in a studio, such as in the control-room window, it is angled to reduce reflections, which can create echoes.
Erect a clothes horse at a 45-degree angle to the longest wall in the room. Hang bed sheets and towels over it. Parallel walls reflect sound off of one another. By positioning a clothes horse off axis to the wall, you interrupt a large portion of the parallel surface. This doesn't eliminate sound reflection but the soft materials hanging on the clothes horse absorb some of the sound.
Remove any glass, porcelain or metal objects from the recording environment. This includes cups, drinking glasses, cymbals on drum kits and bottles. These won't create obvious echoes but they will contribute to unwanted resonance as they vibrate when exposed to loud noise. These vibrations, combined with unwanted echoes, can compound the problem of unwanted sound reflections.
Position microphones equidistantly from the sound source. If you are using two microphones placed at different distances to the sound source, there will be a slight delay in the sound arriving at the farthest away microphone. While this won't generate a natural echo in the room, this delay can approximate an echo effect on the recording.
Turn off any digital delay or reverb devices. If using hardware effects units, remove the patch leads connecting them to your mixer. If using a computer-based effects processor, click "Bypass" on any time-based effects interfaces. Reverb and delay add echo to the recorded sound.
Fix an egg-tray at head-height to the wall nearest to where the microphone stand is. Use gaffer tape or Blue-Tack so you can remove it when you've finished recording. The peaks and dips in the egg-tray surface absorb sound waves, preventing them from rebounding onto another surface and causing an echo.