Glad to see you back bro. Just wanted to say that I relearned driving manual in my STI after a 10 year break. You’ll relax and your shifts will smooth out as you get more comfortable in the car. Keep the radio off and listen to the motor while you drive. Instead of moving to neutral and braking to a stop sign you should try and down shift letting the engine slow the car. Blip the throttle to bring up the rpm’s to match the speed of the lower gear. Great way to learn proper downshifts and eventually heal-toe. Just relax have fun in your new car and before you know it you’ll be heal-toeing thru traffic buttery smooth.
If the car is shaking going into 2nd at slow speeds, you might be lugging the engine below a certain speed. You need to keep the RPM's up. It's okay to slip the clutch a little. Just don't do it for long or high loads. Driving stick in NYC is really trying on the soul. Parallel parking on a hill in a car without hill hold really got old for me. Good luck out there.
Keep your foot on the gas to maintain rpms when you push in the clutch and then re engage. You are letting the rpms drop too low between gears more throttle input especially going up hill... you are experiencing the opposite of rev hang at the higher rpm range lugging the engine. Gearing has nothing to do with speed you can downshift to 3rd going 60mph for more acceleration thereby bumping the rpms into the higher torque range. obviously downshifting to second or first when going 60 is bad because you'll go above red line and its hard on the clutch. If you ride a bike you know when you downshift your legs spin faster but you have more torque or mechanical advantage to climb a hill. Your legs will just have to spin faster to maintain the same speed but it is easier to pedal... the same is true of a car engine. It is easier on the engine to spin at higher rpms in a lower gear. That's why when you are going 60 in 5th your rpms will be low and you downshift to 3rd or 4th when you want to accelerate fast to 80mph of course then shifting back up as you accelerate. you can drive 75 MPG in 4th gear at high rpms and it won't hurt anything under red line except gas mileage. you gear up for efficiency again think bike gears. The forester CVT up shifts round 3500-4000k and it is slow to downshift. The rpms will want to climb when the clutch is disengaged if you keep the gas at the same input. so you have to feather the gas pedal to rev match. You can "drop the clutch" as long as your rpms are in the right range. letting off slowly on the clutch actually leads to more wear on the clutch not less as it is slipping until fully engaged. The goal is to be able to push in and let off the clutch as quickly as you can to minimize burning the clutch up. clutch wear is inevitable as slippage is how they work before they engage and eventually a clutch will need replacing just like brake pads they wear out (but this saves transmission wear). CVT Torque converter replaces the manual clutch. Rev higher between shifts. Subaru's are high reving engines. Don't be afraid to downshift as you decelerate it's actually safer because you maintain power to the wheels and you can hit the gas if you need to avoid an accident. Coasting to a stop in neutral from third isn't safe. As soon as you need to brake downshift to second and don't let up on the gas too much between gears, you can always push the clutch in. When you downshift you won't need to use the brakes as much, compression wind up will help to slow you down. You don't really need to downshift to 1st until you stop completely. Practice dry shifting through all the gears when stopped to get the muscle memory of where the higher gears live. rev higher between gears it is better to slip wear a clutch than lug the engine (the shaking) and unfortunately riding the clutch in first gear is just a reality of stop and go crawling traffic. happy driving! keep practicing you'll get the feel for it.