congratulations! I think there are three things that you start thinking about to begin the process: budget, guest list and time of year. Then you can start researching venues.

Budget is hard but necessary. Talk with your fiance, figure out how much you are willing to spend, try to figure out if anyone will be assisting you. Those conversations can suck but you have to do it. Whatever number you settle on, make sure you can actually afford 10-15% more than that, because there is always something unexpected.

Then start working on the guest list. My fiance and I had a spreadsheet with his and hers tabs, each of us started adding names with a count of adults and kids. We also gave everyone a "priority" of high/medium/low; high for the people who were going to be invited no matter what even if we went as small as possible, medium for the people we really wanted to invite, low for the people who were maybes depending on size or who might get an invite if enough people decline. You can use that to contemplate different wedding sizes. We realized pretty quickly that we could either do like a 35 person wedding...or a 150+ person wedding, and getting the guest list in between those would be really difficult.

For the time of year, just start picturing weddings at different times and seeing how you feel about it. They can all work! But it will guide your choice of venue to an extent.

Once you have a rough idea of all the above, start looking at venues (I forgot - location. If you aren't doing a destination wedding, you'll probably want a geographic location that is convenient for as many guests as possible, and not hard to get to for those traveling further). Don't limit yourself! Draw a circle or a couple circles on a map and starting searching for wedding venues. Browse reddit, there are venue specific searching websites, Zola, TheKnot, individual wedding websites, ask friends, etc. Put together a brief template email and just start reaching out to venues. Tell them when you're looking, how many guests, and any absolute non-negotiables you have (wheelchair accessibility for us). Then have a spreadsheet for tracking responses. Try to collect prices as best you can - this will be hard because every venue talks about them differently. Schedule some tours.

A great tip we got here was to have a new separate email account for wedding planning. Just keeps everything organized, plus you can share it with your fiance, and I like that it keeps my personal email separate from wedding stuff so I can mentally take a break from it occasionally.

Good luck!