The most important guiding principal I follow is:
Only use a well established exchange that is a licensed business in your country.
If they are not and they scam you, or just mess up, then you really have no legal recourse. A legal business is going to require identity papers and verification, etc. Don't use illegal operations as they are 99.99% sure to just walk off with your money.
I quoted you above but I go even further with advice:
I don't recommend ANY online exchange for storage. I read around all over the globe and its too risky. We all understand using an exchange for a transaction to move coins among various clients. e.g. LBC to move coins to someone. If you learn to privately protect your coins you will NEVER be sorry. The other way, where you rely upon the integrity of an institution, is wrought with downsides. With coins on the doorstep of $3K US, the incentive for foul play is prominent.