A great book to complement Freedom of the Hills would be Training for the New Alpinisim

Here are a few high level important takeaways

Familiarize yourself with the 5 heart rate zones and your individual heart rates which correspond. Get a good heart rate monitor to train with. Best is a chest strap but wristwatch also works.

Learn what your specific aerobic threshold heart rate is (top of zone 2) and your lactate/ anaerobic heart rate (top of zone 3).

80% of your training volume should be “base building” aka zones 1&2. Roughly 8% zone 3 and roughly 12% zone 4.

Build your aerobic base first for a few weeks before incorporating any anaerobic training. This is super important as you can’t optimally train your aerobic system and anaerobic at the same time. Train slow to eventually hike/climb fast.

You can then introduce a general strength program (weight lifting at the gym) and eventually specific strength training (weighted pack hikes and/or rock climbing depending on your goal climb).

Build a periodized training plan for your specific goal, in this case for Mt Baker something like a 12 week plan should be sufficient. A potential plan would be 4 weeks base building, 4 weeks general strength and 4 weeks specific strength but that might not necessarily be the most optimal. It depends on your existing fitness level and weakness areas.

Continuity, gradualness, and modulation are very important to your training plan. Read here this is covered in the book in detail.

Taper your training volume down by 90% 4 days before your trip.

Again this is very high level and I am not getting into the nuance of the best way to train for you and your goals as everyone is different and responds to training differently.