If your nervous about something. I'll give you some tips.
lol, I'm not nervous about something, I'm nervous about nearly everything. I never did a game before, or for that matter anything with advanced graphics or any sound. Also developing, testing and publishing something what should run on generic systems in such a time frame is something new to me.
So this will be a very interesting challenge for me.
Well... I suggest practicing then. Make a small engine out of what ever your doing. May it be a snake engine or a platformer engine. Just get used to it.
Your graphics doesn't have to be complicated. Heard of 8-bit graphic style? That should help. A lot.
On the sound, you can use BFXR. An 8 bit sound generator.
Also, stick to one resolution. Make sure it's a commonly used one.
Stick to 640x480 for the most compatible resolution.
Try giving yourself a challenge too. The 15 minute challenge with pre-made graphics, sound and music should help