Another thing to add to your thinking... I found it helpful to think through our needs in terms of the specific problems or pain-points that we wanted to address, not just the spaces we wanted. Explaining our needs to the architect in terms of the problems to be solved helped us be more flexible about the solutions and also prioritize since we (inevitably) couldn't afford to do everything on the list.

Op here - thank you, this all is very helpful! I do have a budget and the names of some recommended design/build and architects. I also know the main gist of what I am looking for with the renovation. But I assumed I listen to the firms without sharing my budget (I guess I assumed that if I give them my budget, them they'll make the work fit the budget, which isn't what I want).

Also, though it will be your last step after they finish, don't forget to budget for landscaping. This project will tear up your yard and you'll need to do some repair landscaping when they finish.

I would decide your true max budget and use 80% of that # to start discussions. Keep that 20% in your back pocket - even if you work through all details up front there is surely something that comes up.

Set up initial meetings with architects and design/builds. Bring your 80% number and a rough idea of what you want to do. They should be able to discuss options at the high-level. Some might roughly draw out ideas for you.

You could then do an initial design for a fixed fee. We paid a few thousand to get a high-level design (not construction-level plans). This went through a few iterations to get what we wanted. Along the way there were other options presented that would be $X more (tap into your 20% here if desired, but save some for construction snafus/unexpected upgrades).

We went with design/build because we only wanted to pay overhead/mgmt fees once (not construction mgmt fees PLUS architect mgmt fees).

We used a design firm. We bumped out the back and did a 3 story addition (basement, main, and 2nd floor). If you know exactly what you want (ex: unfinished basement, new living room and half bath, and master suite), they can give you a ballpark figure (they should ask you about what type of finishes you want etc.). We had one design firm that did a computer drawing that they sent along with their estimate (this was free estimate). The company we ended up with didn't do the drawing until after we paid the deposit. We were able to change the drawings if we wanted.

This is a great answer. You really need to know your budget and try to figure out how much over
can you go. It will probably cost a lot more than you think esp if you are a newbie. Also, start asking
around for referrals on architects, design build firms and contractors.
We wanted to use a separate architect and builder but lots of people go with
design build.

First step, before talking with an architect or design/build firm, is thinking of your budget. Then as yourself, when it costs 20% more, is that ok with you?

ONLY after that do you talk to people, and they are going to ask your budget. Do everyone a favor and tell them the truth, or with a design build firm maybe go 5% below. They will then work with you to help make some decisions, or discuss whether what you want is truly within the budget you have.

This is a long process, and can be very iterative. Just be realistic and open to comments and suggestions.

I want to do a pretty extensive home renovation - bump out to the back to add new kitchen, family room, with new master suite above. I am mentally ready to start the process, but not sure how to begin. I will set up a few appointments with design/build firms and architects, but they obviously aren't going to prepare plans for me unless and until I engage them. But how will I do that without knowing their cost and what their design plans would look like? It feels like a "chicken and egg" problem! Please help this newbie.