Good luck to you! I just completed my first trip in an EV...about 810 miles round trip. One thing I learned was to pay attention to the trend bar on the far left. That is the key to knowing the rate of energy consumption. I started off with a full battery, 175 miles to my first stop and a 235 mile range estimate. After driving a ways at 70 mph into a strong wind and climbing elevation, the yellow downward trend bar dropped all the way to the bottom, meaning I was eating up more range than miles. I had to drop my speed to 65 and even 60 mph at times to reign the trend bar back in. So from the original 60 mile buffer, I made it with about 25 miles left. Since I'm new to this I built in a 35 mile buffer, but as I get better I will reduce this to reduce the cost and time at the EA stations.
After >10 trips of >350 miles, I agree with watching the trend bar AND the miles/kWh. My GPS shows me "miles to go" and I watch this as well as the estimated range (not max OR min). I have never run out of electrons. One thing I do differently is to start out at 5-10 mph below the speed limit. IF I see my buffer range increasing, I can ease the speed up by 5 mph and observe for 10-15 minutes. If my buffer is going down, I slow down. If it is rising, I tweak the speed up higher.
I have started on a 175 mile winter trip with a 175 mile estimated range. But, I knew that on the previous day/drive, I was not watching my speed and rate of accelerations. So on a 55 mph road, I went 45 mph. I used cruise control to avoid that "speed up" tendency. When my range buffer rose to 10 miles (in 15-20 minutes) , I sped up slightly. It continued to rise and when it hit 20 miles (at the 75 mile mark) I drove the posted speed the rest of the way (100 miles). Another time I went on a 226 mile summertime trip, all on a 70 mph Interstate. My estimated range at the start was 234 miles. I set the cruise control at 60 mph, allowed the speeders to pass without hindering their progress, and ended with a 24 mile buffer. Last example: I started a 220 mile trip with a 220 mile estimated range showing. I ended the trip with 100 miles of range remaining! This is because I started at 3200' MSL and ended up back home at 160' MSL.
My rule of thumb is to start slower than the speed limit and increase only after you see the range buffer increasing, rather than starting out fast and having to guess how much to slow down.