The luggage restrictions vary from one airline to another. It is better to have clear information about the luggage restrictions. It is better to go for the normal ones that you can accommodate on the overhead storage when it comes to the cabin luggage. The sling backpack should be in able to store the items that are very much required. Like mobile phones, laptops, and chargers. It is up to you how much you carry the general luggage. The only thing that you need to consider it is the weight restrictions.