Coin Pop-ups are your friend
Selling goods to these pop-up mini missions (the little coins) is not unlike upgrading your residential zones. You are paying resources for an influx of cash. Unlike residential zones, selling resources to these coin pop-ups has no downsides. You still get the cash but there is no increase on demands for your services. No increased traffic levels prompting demands for road upgrades, no utilites over the limit demanding new facilities be built. Even if those items were being saved for a residential upgrade, you can always just re-produce the items you just sold. It costs nothing (but time) to produce items. The same phiosophy applies to the Cargo Ship (which should be built ASAP).
Sure selling items might slow your progression a bit, but you'll have more cash and thus be better able to expand your services when your city grows and starts demanding something entirely new.
Also...if you see a coin pop-up but don't quite have the items they are asking for, but would like the extra cash, just tap somewhere else. The pop-up will remain with the exact same deal. If you tap "No Thanks" it will dismiss the popup and the deal will be lost.
