Hi.
In order to achive that - here is what you need to pay attention to:
1. Use a good quality pasta
(De Checko is my number 1)
2. Use plenty of water - 1 litter for evey 100 gr pasta you are cooking
3. Put some olive oil in the water while you are boiling them, and also some salt
4. Put the pasta in the water while they are boiling and bubbling on high flame.
5. Keep on cooking it on very high heat.
6. Do not overcook your pasta - look at the time on the package.
7. If you intend to put the pasta in a take-away box while it is still hot, - cook it 1-2 minutes less then is written on the package
8. After pasta is ready - strain immedietly, and do NOT wash
9. Have the sauce ready for the pasta - (Never let the pasta wait for the sauce to be ready, you can have the sauce waiting for the pasta)
10. note: In the last minute of cooking the pasta - you can take away some of the pasta cooking water aside in a small cup. You can use this water if/when needed - in case the sauce is too thick.
Enjoy your pasta !