Ideally, the place that works on your Fiero should be nearby. This not only allows you to check the progress and quality of work, but also provides for maintenance and issue resolution.
Word of mouth recommendations are insufficient. Ideally, make a trip to the shop beforehand for a preliminary inspection. Check out the person's work area, their personal vehicle, and other work they have done. Speak with other owners about how that work went, in terms of timeframe, cost, quality, and satisfaction. Unkempt work areas and sloppy work are red flags. If this is a side thing, be aware that their life will delay your project. If there will be other people/shops performing the work, you need to check out the work/workplaces of those people/shops, also.
On your visit to drop off the vehicle for work, be sure to take plenty of detailed pictures of everything currently on your vehicle. You want to be able to prove what parts were in/on your vehicle when you dropped it off. Also make a written list of any and all items dropped off with the vehicle, so you can be sure to get them back.
You need to be informed about the work being done. Know what is involved. Read up on the work you want done. Go over each step with the person who will do the work, and have them write it all out into a contract.
Areas of expertise are very important. Be aware that a person who is a good engine rebuilder may not be good at wiring, for example. Do not push the person into areas of incompetence.
Be very clear about what you want done. Write up a contract with milestone completion dates. The contract should also include time to test drive (at least 200 miles), and monetary penalties for things done incorrectly. Each place that does work should be pre-approved by you, and their work should be checked by you before work continues.
All parts should be run by you (with supplier/part info), prior to install, and you should get post-install pictures. This should be in the contract, and will help prevent cheap parts from being used.
If the person is not doing the work to your standards/timeframe, take the vehicle somewhere else. Things will only get worse.
When the work is complete, do not expect to pick the vehicle up on the first visit. There will likely be things that are not quite right, and will need to be fixed. Get those issues addressed before you pay. Verify all work, all parts, and take a test drive, but get everything right. Only after everything is correctly completed do you pay and pick up.