Let's have a brainstorming session. Ready? Go.
1. Encourage organization among the Syrian opposition. Nothing can be achieved and no help can be sent (in whatever form) until there is some degree of organization and unity within the opposition movement. CNN reports that the "Syrian rebel leadership is split", and various groups claim to be leading the fight on the ground. (http://edition.cnn.com/2012/02/06/world/meast/syria-rebel-leaders/index.html?hpt=hp_c1). Without a unified structure negotiations cannot produce results, aid cannot be given, and coordinated strategy (including possible military campaigns) will be impossible.
2. Any possible effort to aid the opposition or hurt the Assad regime must be in response to a direct request for aid from a unified and organized opposition group. Pleas for help from individuals will not move other nations to act.
My mind goes to Libya, where the National Transitional Council (formed in late Feb 2011) was a player on the scene 8 months before the fall of Gaddafi (Oct 2011). I remember during the lulls in fighting, there were reports that the rebels were training and organizing (this was when there were rumors that CIA or MI6 had people on the ground in Libya training the rebels.) Now I have no idea if this was being organized by the NTC, but the fact that groups of fighters were able to be trained for a coordinated campaign shows that there was at least some structure. Libya also has the advantage of vast stretches of desert where training was possible out of the reach of Gaddafi. Syria doesn't really have that, but it does have a border with Turkey...
3. Turn Syria into a pariah state and build a coalition around that concept. Let's face a fact: Iran isn't massacring its citizens. Syria is, and everybody can see it. Therefore, if Russia and China won't allow a UN resolution meant to transfer power from the Assad regime, make the Assad regime unprofitable. In effect, indirectly help the opposition by hurting Assad, thus making their job easier.
The link between Syrian and Iran isn't to be ignored either. I haven't read any news reports mentioning this, outside of a report on Al Jazeera that there might have been Iranian snipers operating in Syria (though, rightfully, the report was skeptical in tone and showed how those shown in a video of the alleged snipers closely resembled a photo of a group of Iranian engineers missing in Syria).
Washington should be working to separate Damascus and Tehran, not drive them closer together, if at all possible. Though, according to Ayatollah Khamenei, as quoted on Hezbollah's English website (yeah, they have one: http://www.english.moqawama.org/), the US is orchestrating a plot to punish Syria because Syria "supports Palestinian resistance and Islamic resistance in Lebanon", however, "Unfortunately, some other countries and some regional countries are participating in the American plot". Yeah, those other countries include the entire security council (including Morocco). I guess Tehran and Damascus will be desperately holding on to each other for the foreseeable future.
4. Get the Arab League to grow some claws. They need to lead this charge. I think Obama played it brilliantly in Libya by not waving the American flag in the faces of those who didn't ask for it. Keep it cool. Let the regional players settle this in the way they deem best. After all, they live there and they will deal with the consequences first hand. Offer US logistical and technical support when requested.
Turkey is also a major ally here. I'm glad to read that Ankara plans on picking up the pieces of the failed UN resolution and coming up with a new plan. (http://www.reuters.com/article/2012/02/07/us-turkey-syria-idUSTRE8160RO20120207)
5. Should things continue to go sour and should the Syrian opposition get its act together, what would be the next step? I hate to say it, but a Limited War doesn't always have to mean military deployment. It could mean a cyber-offensive. The possibilities are endless in this respect: the power grid, command and control, communications, etc. This would be a declaration of war against Syria, so I'm not for it. This is a brainstorming session, after all.
6. Berlin Airlift-style campaign. Dropping food and medicine into a country isn't necessarily an act of war, rather, it's a humanitarian gesture. One must expect Assad to consider this an act of war, but would Assad really commit himself to a war when he's fighting a revolution? Either way, dropping supplies is logistically going to be relatively simple, especially with Syria's border with Turkey.
The argument can be made that supporting the opposition would only prolong the strife, inflame a civil war, and increase the body count. I think it's a valid criticism, but I don't think that that's our decision-- further underlining the need for the opposition to unify and organize itself. Ultimately, only Syrians can choose the next course to take.