It can really depend where you live so I think the first advise is to take it easy on yourself.

• It is ok to combine ways of transports, say cycle to the first train/bus then load the bike on it/park at the station
• Start with a sturdier bike, the one which is bigger and more visible in traffic and gives you a better sense of control.
• don't expect cars to respect you because you cycle or to know what to do around you. Bad drivers are everywhere. Don't try to prove points. Safety is more important than ego.
• get yourself a good, large backpack. This will be your new back seat
• Take taxi/uber when needed. I once arrived to a friend's wedding held out of town in a taxi and literally everybody I knew there looked at me as I was either a fool or a millioner. The bill was like 35$. Way cheaper than owning a car.

Lastly, enjoy how good you will feel. Climate protection and all that is great but your body will love you for it and you will feel it. Good luck