I've been on Twitter for one week, and this is what I've learned so far. But first, you may want to check out this article and this article. I do not agree with every bit of advice in there, but there are some really good ones.
1. The picture. Choose a picture that really stands out. You want people to really notice your tweets, and that's not gonna happen if you select the wrong image. Use primary colors. Do not use landscapes. Do not make cute faces, unless you are a really (and I mean really) cute female. If you are particularly unattractive (I know, there is no such person) you might consider some other image to represent you.
2. The name. Try to use a person's name, not a business name. You are not a Japanese restaurant, you are the guy running the Japanese restaurant. You are not a bag of chips, you are the guy making the chips. In short: be a person, not a product.
3. The twits. Do not twit too much. Make them interesting, funny, informative or all in one. Do not talk trash and unless you are a really big star avoid talking about yourself. And again, unless you are a really big star, do not ask a lot of questions.
When you're sharing a picture or a video, take a few minutes to write a great, catchy and interesting description. Don't just say "I liked this video on youtube" or "I posted a photo on Facebook" or Instagram. That's 99% sure to get you booted off a few of your follower's lists. Do not share pictures of children.
4. The topics. Choose an art, a science and a sport. Stick with them. Try to practice them and be good at them. Find things that are funny, interesting or both, not necessarily new and unheard of. Try to share what you know, not what you think about what you know. You don't have to be original. If you see something worth re-twitting, do it. But again, don't overdo it.
5. The followers. Follow as many people as possible. Go to some really popular person and start following his or her followers. (Be careful not to break the rules, though). Some of them will follow back. Do not talk about them or with them. Remember they are people, not numbers. Talk to them by name, if you have to. If you say "I've made 100 followers this week and lost 16" ... the next message you receive will probably just say: "17".
6. The conclusion. There are a lot of people on twitter trying to sell something. Don't do that. Your goal is to bring value from outside the system in. If you do that people will notice. Value generates value.
Oh, and one more thing: Speak English. Not everybody understands Russian, Spanish or Greek, and you may get the boot just for that reason. Besides, why limit yourself to one tiny audience, when you can have the world?