Coming to Montenegro ? (Podgorica)

Hello dear friends,
I'm coming to Montenegro for one week holiday this Friday.
I will be staying in Herceg Novi. I know this is Podgorica community but I was wondering if you have any tips/suggestions on what to do and where to go (or where NOT to go ?).
I would like to take day trips from Herceg Novi. What is the best way to get around? Do I need to rent a car or are there trains? Are the distances far from city to city?
Basically, any advice, tip, warnings you have will be much appreciated and welcomed.
Would love to return a favor and give you tips about Israel, Amsterdam, Thailand and more :-)
Thank you so much,
Hilla