My 1998 Intrique is heating up what is he first thing that I should check?

The first thing to replace would be the thermostat and use a good quality 195 degree temp. has the coolant been changed in the last 5 years? GM vehicles from 1996 to present use Dexcool coolant. it should be flushed out and changed every 5 years even though it is an extended life coolant. it is possible the radiator is getting plugged up and that will cause overheating.
have the radiator flushed out when you change the thermostat and use a 50/50 mix of dexcool and water