The heat on my 2000 Ford Taurus is not that good. Takes forever to heat up, but still not that good. Turning the fan up on high makes it worse. Best lukewarm heat is turning my switch to halfway on fan. What can I do to get better heat.

These cars are infamous for coolant contamination cause restrictions in the heater core. i suggest performing a heater core flush followed by a complete cooling system flush. i have seen this dozens of times in these cars and this has been the fix nearly every time. good luck!

Quick fix:
Assuming everything else is in working order and your antifreeze is at the proper level and mix and you are not losing coolant you could put cardboard in front of half of your radiator during cold weather months to raise the temperature of the coolant thus resulting in warmer temperatures from your heater. Be sure to watch your temp gauge/light and do not cover your entire radiator as you do not want to cause overheating. Another option is to replace your thermostat with a higher temp one. Hope this helps you!