A few useful tips about packing in general:

1. Check your limit. Airlines have different limits regarding weight and size of luggage you can take. Both checked baggage and hand luggage. They are also different in each class, so check it BEFORE buying your ticket. Maybe it would be better to pay a little more and bring larger suitcase with you. For me it was 23 kg and 10 kg.
2. Check what items apart from cabin baggage you can take with you. There’s really a lot of stuff that you can take, which won’t be counted into you limit. I was really surprised to see that I’m allowed to bring not only laptop, camera, hand bag and umbrella, but also a bunch of flowers with me. 
3. Check what you mustn’t take with you onto the plane. For obvious reasons.
4. Pick up a suitcase that is both light and comfortable to use. Remember that the wheels are important! Cheap wheels will make the whole suitcase bounce. You don’t want 23 kg to bounce in your hand. 
5. If you have the possibility, check the weight of your luggage a few times during packing. You will be surprised how heavy a few things may be.
6. If you’re buying a suitcase, buy one that’s colourful. It will help you spot it fast at the airport and help you recognise it. If you have a suitcase that’s black or navy blue or brown, be prepared- these are the most popular colours and there will be a lot of luggage similar to yours. On this moving tape they all look the same. Make sure to add a detail that would help you recognise it sooner- like a colourful ribbon or a tape (just don’t go for red, everybody uses red). And make it big, since the smaller ones may just end up at the part of the suitcase that's facing down or away from you. Even if your suitcase is colourful and original, make sure to add some detail just in case.
7. Make sure that your data are written somewhere on your suitcase. Best are: your name, phone number or address. It will help in case of lost luggage. Most suitcases have a special pocket for personal data, so you don’t have to worry that everyone will see it- just the right people in case it’s necessary.
8. Make sure your suitcase suits your needs. You can buy plastic or material ones. I’m a fan of material ones, so here are some pros: 1) they are more flexible, so you can shape them with your stuff and pack as much as you want. 2) they are soft. This is a thing people usually overlook when choosing a suitcase for cabin luggage: if you want to store your laptop there, plastic suitcase is hard and will protect it from direct hits, that’s true. BUT it’s the suitcase you’re taking with you, so you will probably not bump into things with it- it’s not the one that will be thrown around by airport staff. So, the thing most dangerous for your electric devices would be vibrations and material suitcase would damp them, while the plastic one would only accelerate them. I've never used plastic suitcase so any pros for them in comments would be welcomed ;)
9. Remember that the weighing machine at the airport may be calibrated slightly different than yours. Make sure that you have a few digits left to your limit.
10. Check the fees for overweight luggage. In my airlines the price was 100 Euro if the weight was more than 23 kg and less than 30 kg. Yes, it doesn’t matter if the weight is 24 kg or 29 kg, the fee is the same. 
11. Check what kind of snacks will be served on the plane and how long you will have to wait, so that you can prepare food for yourself. Of course, there are shops and restaurants and cafes on the airport, but the food there is more expensive. Some snack from home won’t hurt. Plus, there’s a possibility that the food at the airport won’t be something you are used to or something you can recognise. 
12. Don’t take water with you, unless it’s in a 100 ml bottle. The security will force you to throw it away because of ‘all liquids in 100 ml transparent bottles only’ rule. “But it’s in sealed bottle, surely they won’t ask me to leave it!” Yes, they will. You will be surprised by amount of sealed water bottles in the trash bins next to security check.
13. You can take cosmetics with you but they have to be in 100 ml or smaller transparent bottles and in sealed transparent bag. Yes, the security will throw everything else away. No, they won’t be convinced by your sad expression or the brand name of your mascara on the original container. And the bag must be both transparent and sealed, they usually ask people to throw away a whole bag if it's not sealed.
14. Do not put any valuable things into your checked luggage. No money, no jewelry, electronic devices would be safer in hand luggage too. Don’t risk them being stolen. 
15. Put everything you will need the first night and day into hand luggage, in case of airport sending your checked luggage somewhere else by accident. It takes a day to a week for it to be returned. This applies to: underwear, toothbrush and toothpaste, hair brush, clothes for the first day, chargers, etc.
16. You can take your medicines with you in your checked luggage. I would strongly advise to keep them with their description pamphlet (you know, the one that was in a box with them that list all the ingredients, purpose and how to use), the original container won’t hurt too, and keep them somewhere on top, where they can be accessed easily. Security may want to check them (they’ve checked each and every one of my meds) and this way they not only can make sure that they are not suspicious, but can do this without going through all stuff you’ve put in your suitcase. It gets more tricky in hand luggage (rules are more strict), I've never had meds in hand luggage so I can't really say anything about it.