first-timer here...
i'm trying to go to havana next month (june). am open to getting there from mexico city/nassau/wherever. does anyone have a preference based on their experience getting there from the states?

Toronto Canada is a good choice.

You don't mention from where you are travelling in the US and that makes a difference, at least from a cost standpoint. Assuming you are travelling unlicensed by the OFAC there are also some other things you have to take into consideration, the main one being do you have to clear US Customs and Immigration at the foreign airport where you will be arriving from Cuba.

In Canada and the Bahamas you will have to clear US Customs in Montreal, Toronto or Nassau. If you are returning to the US from any of those cities on the same day of your arrival from Cuba there have been posts from persons who have said they were questioned about whether they had travelled to Cuba. Assuming that you haven't listed on the Customs declaration form that one of the countries you visited was Cuba, how you answer those questions is up to you.

On the other hand you do not clear US customs and immigration when you go via Mexico before your return to the US. You clear US C/I when you return to the US. I have only seen one poster on any board who has reported being questioned about whether they had been to Cuba when returning from Mexico. Especially if you are returning from Cancun there is no reason for US C/I to suspect that you may have travelled to Cuba.

Cancun is probably a better gateway to Cuba than Mexico City, simply because there are usually cheaper charter flights going from many US cities to Cancun and the airfare from Cancun to Habana is quite a bit less than flying from Mexico City to Cancun.

When travelling to Cuba from the US you should always use a birth certificate and drivers license when entering the gateway country, whether it is Canada, the Bahamas or Mexico. You should discard all your Cuban tickets before you clear US C/I and probably not try to bring back any Cuban products, souvenirs, Cuban guidebooks or other Cuban memorabilia on the off chance that you get searched. You should not list Cuba as a country visited on the customs declaration form unless you are trying to make some political point. You should re-enter the US from the gateway country with the birth certificate and drivers license (or other photo id) and not a passport because you may have been stamped on your entry and exit from Cuba with the "bank stamp."

Bottom line is the chances of being challenged are slight. Thousands of US citizens travel to Cuba in violation of the regulations without a problem. You can reduce the slight risk by doing what I outlined above. If Cancun or Mexico City is a cost effective gateway then the slight risk is reduced.

You have two options to fly to Cuba from Mexico. Mexicana or Cubana from Mexico City. Aerocaribe (a subsidiary of Mexicana) or Cubana from Cancun. You can make reservations directly with Mexicana for either a MC or Cancun departure by calling Mexicana in either Mexico City or Canada, or with either Mexicana or Cancun by using a Canadian or Mexican travel agency. However you do it, you can buy the Cuban tourist card at the airport in Mexico if you don't get it by using a Canadian or Mexican travel agency.

Good info from Altahabana. As he says, Cancun is cheaper than Mexico City. You can also look into flying in from Jamaica or Canada (Toronto, Montreal.) You will get a lot of opinions as to which way is better but I would decide based upon how convenient and cheap it is to get to your gateway city.

Yes you can be questioned about being in cuba when you return to usa from cancun. Gowever it is easier to travel to cancun abd then get very cheap package to cuba from cancun .So many flights go to cancun that is what makes it quick and pretty painles. to see cuba check my website www.wolfcalls.com

Cancun-Havana was incredibly easy for us. Plan on $180 RT plus $20 tourist card for a noon flight to Havana.

Felix is quoting the price for Cubana and I'm not sure that you can get the $180 fare very often when you include Mexican departure taxes.
The problem with the Cubana flight is that it leaves too early for most travelers to make a same day connection. If you plan to spend some time in Cancun or the surrounding area before you leave for Cuba then it is definately worth considering since it is about $100 cheaper than Aerocaribe. If Cancun is just your gateway though and you don't plan to spend some time there the cost of having to stay overnight with transportation to/from downtown and the cost of meals and even a bare bones hotel will eat up much of the savings over a same day AC flight. Most people can make a same day connection to Cuba from Cancun on the evening AC flight when arriving from the US.
The Mexican departure tax also varies depending on how long you have been in Mexico. If you are in transit and making a same day connection it is considerably less than if you overnight. You need to save your boarding pass from your incoming flight in order to get the lower tax.
Another consideration you need to take into account when flying Cubana is their bad on-time record to and from Cancun. I believe the return flight from Habana leaves and arrives at 10:45 am (l hour flight--l hour time difference). One of the two times I flew Cubana it was three hours late in leaving Habana but fortuneately my connecting return flight to the US was early evening. I have heard many persons in Cancun complain about late departures on Cubana.
In summary the cheaper airfare on Cubana may not be much of a savings if it requires you to overnight in Cancun when you could otherwise travel to Habana on the same day with AC, and even more so if Cubana is delayed out of Habana and you miss your return connecting flight out of Cancun.

... for all the advice. as it turns out, this time around i'll be going with an official license. but i'm thinking that next time i might go the cancun route. will see how this goes...