First off, Let’s define what a headlight aim is. Properly aimed headlights are "square" to the ground vertically. They are also parallel to each other and the car’s centerline horizontally.

"But the front of the lamp isn’t flat! How do you square a sphere?" Look at the front of the lamp. Do you see 3 little tabs sticking out? The tips of those 3 tabs create a flat plane in space. It’s that plane, not the front of the lamp, that is actually used to aim the beam pattern.

The poor mans headlight aimer
You need:

2 pieces of plywood big enough to hit all 3 tabs on the lamp but not so big they hit things near the lamp. If the lamp face is curved too much for the plywood to hit all 3 tabs then glue small blocks to the plywood. Make sure all 3 blocks are the same thickness. The plywood and any needed blocking must only touch the 3 tabs.
A level. The best "level" is one of those combination squares with the dial level like carpenters use. Any small 3-tube level will work in a pinch.
A long straight edge. This needs to be very ridged. A piece of steel pipe will also work.
Horizontal Aim:
You’ll likely need help with this but only because there are too many things for one person to hold still. This is really easy on Fiero because no grill blocks access to the lights.

Put both the plywood tools you made against the headlights and hold the straight edge against them.

Adjust the horizontal screw until both lights are flat against the straight edge.

This step has taken care of both the lamps being parallel to each other and the car centerline.

Vertical Aim:
Park the car on as smooth & level a surface as you can find. This will work best on concrete or black top.

Lay the level on the ground in line with the car. Look carefully at the bubble and don't forget where it lines up. This step is important. It compensates for any slope of the ground.

Put the plywood tool against the 3 tabs on the lamp.

Put the level vertically against the plywood.

Adjust the lamp until the bubble matches where it was on the ground.

The lamps should now be very close to their designed alignment. If you still don’t like the beam pattern then it’s the lamps themselves that are your problem. Try another brand/type of lamp, as each is different. There can be radical differences from one lamp brand/type to another. This is why it’s important to replace headlamps in pairs whenever possible.