The link below is a copy of the DIY suspension install I wrote awhile back. I've been meaning to offer up a rewrite on the process for the front for a long time. But either I didn't have the time or it was out of side out of mind. Using a spring compressor while the front shock/spring is still mounted on the car is out. I make mention of the 350Z at one point because I actually typed this up first for a post on my350z.com
As a courtesy I'll spell it all out.
Remove nut on sway bar end link on suspension control arm.
Use floor jack to compress suspension upwards to relieve pressure on the sway bar end link bolt, you goal it to push the bolt out of the suspension arm.
Remove lower bolt on shock/spring assembly, you may or may not need to use the floor jack to adjust pressure on the suspension in order to free the bolt.
Unbolt the brake line from the shock, push off the speed sensor lines off the shock.
Look up at the bottom of the upper A arm that's closest to you. See the cotter pin in it. Remove that pin, your not going to be able to reuse it, replace it with a 3/32" by 1" pin on reasembly.
With the cotter pin out loosen the nut above it and turn it about 3 turn's. Since the A arm usually sticks in place on that bolt, you'll need to tap or whack the A arm with a rubber mallet to pop the bolt free. Once you get it free now take the nut off all the way. BUT be carefull once you do, the entire suspension will flop free and to the side, don't get hurt.
Now pop the hood of the car if you haven't already done so. Break free the 3 nuts that secure the top shock mount, removing only 2 nuts. On the 350Z IIRC you might have to remove the strut tower bar, though I could be wrong. Reach into the wheel well with one hand and grab the shock/spring assembly and push upwards while with the other free hand you undo the last upper shock mount bolt.
Guide the shock/spring assembly out of the car. Be very carefull at the fender lip, easy to scratch.
With the shock/spring assembly off the car it's time to deal with getting the spring off the shock. Some Z owner's may elect to not use a spring compressor, be carefull if you do.
When you get to the point of needing to break free the bolt the secures the shock to the shock mount here's how I figured out to break it free even if it's really on their hard.
Use the wrench in the middle of the picture, got mine at Sears 17mm and 19mm.
Use that wrench and a cresent wrench in the following order.
Place the shock/spring assembly on the highest grip surface you can find. Grab the wrench, put your foot on the whole assembly and pull back with as much as it takes to get the nut free.
Hope that helps,
Repeat on the other side of the car of course.