I personally am not very good at drawing/illustration. I do programming outside of games, recently been messing with the Bukkit API for Minecraft servers to write my own simple plugins. Most of my coding is done in Java; I write applications in my free-time. I've become very accustomed to writing Java code and I want to use this game jam to push myself. Since we still have 7+ days before the jam starts, I'm going to figure out what other language I will be writing in for this jam. 

Ultimately, the choice is yours in regards to the vast selection of languages and pre-written game engines that come free with marketplaces that can many times contain free game assets. I've personally never participated in a game jam but what I know for certain is that not setting a scope or milestones to a project can quickly lead to disaster. Games are meant to be fun! While we don't know what the theme of this game jam will be, of course it's optional and meant to inspire rather than restrict, use this time now to help narrow down what it is you will be doing for the duration of the game jam. Are you going to make an artsy type game that relies on atmosphere and charm? Or do you have a simple gameplay loop that you think could be delivered on schedule with room for the project to grow? Do you have a previously brainstormed world-lore that you want to bring to life through NPC dialogue?

In a universe of choices, make yours wisely. Take the time now to look into just how your game will be designed. Network with other first time jammers of different skillsets to learn new things and challenge what you preconceived yourself being capable of. Dream, but set a destination for that dream to take place. Don't overwhelm yourself with the next AAA game concept. Make something that feels unique and true to you as a creative individual. 

Best of luck to you!