To change the timing belt on the 1.8 liter engine, I strongly recommend using a cam sprocket locking tool and leaving it in place while removing and installing a new belt. Cam sprocket timing marks on this engine are really confusing and GM even sells a special (but pricey) cam sprocket locking tool with a little window which shows the left cam sprocket offset timing mark. I had my GM dealer print me a copy of official GM service manual procedure for timing belt change before I did mine. I did the job right first time, no problems.
One of the oddities on this car is that the harmonic balancer pulley mount bolt has a star shaped head which requires a star socket for removal. Factory service manual also recommends replacing the timing belt tensioner pulley bolt with a new one