These days if you are trying to travel on the cheap it is an absolute necessity that you cut down on the amount of crap that you bring with you and let's be honest, most of the stuff that we bring with us on trips is completely unnecessary anyway. I know the old saying about how people will pack so much underwear that it looks like they are planning on crapping themselves multiple times a day and well, i've been victim to this before in the past as well.
There are some rather awful airlines that seriously restrict the size of your carry on these days and even worse ones like Spirt airlines that will charge you for a standard carry-on bag but with a bit of research on your part you can suss out which is shich. In my two decades+ of travel I have never encountered an international flight that had massive restrictions on baggage but I have encountered several that restricted the size of your carryon but even then for the most part unless you were seriously violating the rules, they let you take whatever you want on most of those flights.
But I do recall the very first time I went on a "long trip" which at 20 days, it turns out wasn't very long at all. I loaded up my borrowed backpack and kept trying to reduce the size of it over and over and though i had done a pretty good job until I arrived in South East Asia and quickly realized taht most of what I brought with me was completely unnecessary.
Let me help you out with how you can reduce the size of your luggage and maybe ,just maybe get you to understand the importance of trying to get yourself to carry-on only.
Unless you have specialized toiletries, you do not need to bring any of them with you. Believe it or not, people all over the world both bathe and brush their teeth
you do not need to bring a plethora of t-shirts. Especially if you are traveling to a tropical place, the materials they make your shirts out of is probably FAR TOO HEAVY for the climate you are going to and once again, people all over the world buy and wear clothes. If you find that you in fact do need a shirt, trust me, it will be offered to you constantly and will not be difficult to find
you do not need to bring multiple pairs of shoes with you. You might think you are going to be trekking off to the jungle lands but chances are, you are not going to and if you do there will be a place that rents high-quality boots for something like $1. Just do that. Otherwise you are going to be running around like a tool with pair of Timberlands tied off the end of your bag the entire trip. I know this because I was that guy.
Everywhere in the world... EVERYWHERE, has washing machines and normally, and especially in the poorer places with the wonderful beaches that you definitly should visit. They will have places that do your laundry for so little money that it would be foolish to overpack. Do you have a favorite shirt that just makes your eyes "pop?" Ok, bring that shirt, you can wash it along with your socks and underpants that you almost certainly brought too many of with you for so little money that it is of zero consequence. It will probably return to you cleaner than it has ever been before as well.
Trousers: one pair maximum. This is another one of those things that it depends on where you are going. If you are going somewhere tropical and you are from a place that has winter, the weather is almost certainly going to be oppressively hot in your mind and therefore wearing trousers is something you really aren't going to be doing very often. There are some places where trousers are required such as religious sites but if this is the case you are once again much better off buying some lightweight trousers made locally. Plus now you have an unusual pair of something you can wear in the summer back in your home place and have a story that goes along with it!
Bring flip flops only if you have huge feet. In all of these tropical places flip flops are sold in every single minimart and every single tourist clothing shop. They will cost next to nothing and probably arrived on a shipping container from China for 8 cents a pair. The only caveat is if you are a huge person. I am a relatively tall person and it is difficult for me to ever find size 12 shoes anywhere in my travels. The good news about flip flops is that they tend to be flat and easily fit in any carry on.
Once I ditched the checked bag aspect of my travel life I found that things started being a lot better for me on my travels. Less is so much better even if you have to repeat outfits frequently. Nobody will know except you unless you don't wash them and start to stink... and well, you should be doing that anyway.
The bottom line is that most people travel with way too much stuff and they don't even end up using most of it. If you just cut down and travel in a minimalist sense you will find that you have a much better time as well because you are hauling around less crap and your decision about what to wear on a particular day will probably be dictated by whatever is clean.
If you need another reason here is one: When is the last time that you heard about a carry on bag getting lost or being delivered late? Unless you lose it, that isn't going to happen.