Yes, take care of the engine first. Small bolt ons would be a good starting point if you're on a tight budget. I'm not too familir with civics but these would be some good additions with decent gains, power and 1/4 mile wise. Home-made ram air and K&N filter, short throw shifter and aftermarket clutch, cams, cam gears, header, cat back, pulleys, and a very small shot of nitrous (something like 50). That's somethings i got off the top of my head. Like i said, i don't know too much about civics. You might want to check with some of the civic guys first.
Or if you've got some cash or want big power, you could do what i plan on doing and steer right towards forced induction or engine swap. I plan on going big first, and small later.
Good luck.