There is one simple principle governing this aspect of traveling: travel lightly. For the most part, I had only a small suitcase and a shoulder bag as shown above. At other times I did have a third piece of luggage: a small backpack. But carrying all three was a bit hard so I ended up giving away some stuff, posting other stuff back home and giving away the backpack. Just the two pieces of baggage was much more manageable. There were many occasions on which I had to run for a train or couldn't find a taxi or bus and had to walk a considerable distance. Being able to walk and carry everything is a big advantage.
You don't need much to travel. Just clothes, toothbrush and toiletries (just the minimum - I used hostel soaps rather than carrying my own), a book to read. I didn't have a towel, just a sarong that I used as a towel when needed. I also had a laptop computer in my shoulder bag. I had one pair of shoes and one pair of sandals, always wearing the shoes when traveling so I could put the sandals in my suitcase. I carried only one, thin jumper and bought a thick jacket once I reached colder temperatures in Russia. I had only a thin jacket until then which was a bit of a pain to carry in Asia where I hardly ever needed it.
I did buy souvenirs as I traveled but posted them home at the first opportunity. That can cost a bit, but not too much, and it's better than carrying them around with you. All my packages - from Australia, Southeast Asia, China, and Russia, arrived safely home.