Traveling to Cuba from the United States is still banned by the U.S. government. If you are from basically anywhere else in the world, you can travel to Cuba with ease.
For those looking to travel to Cuba from the U.S. and who do not have an approved visit for things such as government duties or journalism, there are still options.
For those living in the far north of the U.S., you can travel to Canada and then down to Cuba. Some are worried that they will be turned into the U.S. government since Canada has such close ties with the U.S. Canada has regular and legal flights back and forth from Cuba for anyone, except technically U.S. citizens are not supposed to do this.
My recommended way of travel is to fly to Cancun and then on to Havana, Cuba. Cheap flights are often available to Cancun. From there, you can fly on either a Mexican Airline or a Cuban airline to get to Cuba.
Make sure to pack only carry-on, that way you will not have to worry about checking bags. At the Cancun airport you will to leave the terminal dedicated to US flights and go to the terminal which has other Latin American flights.
Cubana de Aviacion is the easiest airline to use on your way to Cuba, as it has regular flights and they accept US credit cards. It will likely be billed through a 3rd party, but I have never heard of any problems.
Buying tickets or hotel rooms from the US for Cuba is the same as trying to buy things in Cuba with a US credit card. IT WILL NOT WORK. No US bank associates with Cuba, so make sure you have plenty of cash.
Your cell phone will not work in Cuba either, and free Wifi is very hard to come by.
Hotels are not that cheap, but you can choose to rent a room from a family. Some of these seem like a bed and breakfast, but many of the rooms near the Malecon have private entrance rooms for around $40 USD per night. These are called Casa Particulars and you can book them online without having to pay anything up front.
Contrary to popular belief, most Cubans love Americans. Violent crime is low and very few have guns. Pickpockets are about the same as everywhere, so just play it smart and you will be fine.
I would not recommend trying any local street drugs, as punishment is harsh in Cuba. Avoid talking politics with anyone, and be careful when photographing officials or po
Make sure you brush up on some Spanish and be ready to salsa dance your ass off.
Naturally most are worried about getting in trouble when returning from Cuba to the US. The truth is that there have been no prosecutions of US citizens for traveling to Cuba in over 5 years. It is not a priority for the Obama administration and there are no judges dedicated to doing this.
When returning through Cancun it is recommended to stay at least a night in Cancun before heading back to the US. This way if you are questioned you will have receipts and proof that you visited Cancun and did not just use the airport.
If you give US customs no reason to think you traveled to Cuba, they should have no reason to even bring it up. Cuba does not stamp your passport when entering Cuba. If you have an extra Mexico stamp from returning from Cuba, it is likely ok. The chances of US customs noticing it is slim.
Do not bring back any cigars or items that can not be purchased in Mexico.