I have been messing with these for about 20 years. I originally bought a slow old ITC Civic to have fun with and learn a bit about the cars. Not a lot has changed, you still cant find parts for them and if you are wanting to go fast, there are MUCH better ways to do that.
So if you have one here are a few tips.

1. Search on eBay and get a FACTORY manual. They are usually under about $20 USD, maybe get two if they are cheap. Mine has come apart with use and age. I am glad to have a backup. The aftermarket manuals are not the same at all.
2. The weber DGV conversions SUCK! Not recommended at all. The fuel bowl is not oriented correctly with the store bought kit and its just not the best way to go. They can work to put put your car back and forth, there are better choices though.
3. Pertronix or other copycat electronic ignition is a worthwhile improvement.
4. Change your timing belt. Start fresh and look at the water pump closely too. Water pumps are one of the parts that are harder to find. Local water pump rebuilders may be able to help refurbish your core,
5. Some parts are very hard to find. Transmission synchro's, rocker arms all sorts of parts you take for granted on the 88+ cars are not available without some serious searching or some serious cash to bribe someone who does have them to part with them.
6. A D16 swap is an option. Will it be faster than an 88+ with the same engine? NO! Not if there are any corners or braking involved. The later cars are a little heavier but the suspension, brakes, etc. are more advanced. The swap does help the parts supply problems mentioned above though and FI is nice if you keep that. So you will be doing a LOT of fab work for something that would just bolt into a newer civic in a few hours work.