While this question is very open-ended, there are a few general items that can help, in my own experience.
You might consider a 'Session 0' to hammer out exactly that, or if game has already begun, there's nothing to say you can't take a couple hours out of play to examine the game and make adjustments to your plans to better accommodate player preferences. It's a good idea to periodically pulse check the game like this anyway and keep the game healthy. That said, you asked about making sure quieter players didn't get steamrolled, so the rest of this will focus on that rather than on session 0 stuff.
Proactively ask the quieter players what they want to do and do not let anyone else interrupt them. Be prepared to calmly and firmly say something like 'Hold on, we'll get to your input in a moment, but everyone should have the space to contribute.' and give the quieter person time to think a little and then give their input. Since singling people out could cause some anxiety, doing this for each player in sequence, around the table for Social or Exploration times or in initiative order for Combat times will ensure everyone has an equal chance to be heard.
Make efforts to ensure that the quieter people are comfortable.
Quieter players may have a lot of reasons for being quieter. Some may just be a bit laid-back or introverted, others may have anxiety issues or just be shy. The gaming table should be a safe place for expression and participation. Find out what motivates the quietness and ensure the environment of the gaming table is a positive one for them. This means that if they tend to get talked over or if they automatically yield focus when someone else speaks up, be ready to ask the more boisterous person to hold off if you feel they are speaking out of turn. It's good for players to be excited, but not at the expense of the others at the table.