Former Del Sol owner here.
Read this sticky at the top of the forum. Lots of good info here condensed into an easy to read list. No need for trolling.
65+ Vehicle modifications for better fuel economy - EcoModder.com
If you want a quick list, here's my recommendation (in this order)
1) practice driving style
100+ Hypermiling / ecodriving tips & tactics for better mpg - EcoModder.com
2) pump up tires to sidewall psi max
2) get mpg instrumentation (mpguino or similar)
3) install a kill switch