Separate the three environments
A cold pavement, a crowded train and a heated office are three different places to dress for. One heavy layer may solve the first and become inconvenient in the other two. Think through where you are likely to remove something and where you will put it.
The layer next to the body should be comfortable on its own if you expect to take off a cardigan or jumper. Check the neckline, sleeves and transparency before treating it as an invisible base. A coat should still close comfortably over the layers you actually intend to wear.
Leave room at the sleeve
Bulky cuffs can collect inside a coat and make it difficult to bend the arm. Try a fine knit beneath a roomy coat, or a jacket with sleeves that accommodate the jumper. If you have to tug the inner sleeve straight every time you put the coat on, the combination may be more trouble than it is worth.
A scarf can add warmth without committing to another full garment. Choose one you can put in your bag when the carriage gets warm. A large wrap may be pleasant outdoors but awkward if it occupies all the space needed for the rest of the day.
Consider the carrying stage
You may spend part of the commute holding the coat rather than wearing it. Long hems, trailing belts and unsecured scarves can become awkward around doors and stairs. Fasten or contain loose parts and keep your hands available where needed.
Check the bag strap over the outer layer too. A strap that sits securely on a thin shirt may slip off a smooth coat. Crossbody straps need enough length for the extra fabric without pulling the jacket out of shape.
On the return journey, the weather and your energy may be different. Keep the combination simple enough to reassemble without a mirror. The best arrangement for your commute is one in which each layer has a job and you can remove it without dismantling the whole outfit.
