Many people remember to take the sewing machine but forget necessary parts like the foot control, the power cable, the extra feet, extra needles - so be sure you take all of those. Also I think it is helpful to take along the manual to your sewing machine, just in case you have a problem and need to look something up.
It's also helpful to have some kind of box, like maybe a plastic shoebox, that you can put your supplies in while you're sewing so that they're readily accessible but not floating around on the table, which may be shared by many people. Mark your supplies in some way so that you can tell which ones are yours and not grab someone else's by mistake.