I'm using Aperture too. Here's is my far-from-perfect workflow. It works for me, but not always.
My point is to start trashing as many shots as possible, and to keep only good or important ones, so later I can give more attention and time to a small, manageable, number of really good ones.
Important: I'm using a managed aperture library, so I keep originals in my date-based folder hierarchy.
Since I want to keep as more information as possible inside original pictures metadata, I geotag and tune time in the images BEFORE importing them to Aperture.
- I don't import pics right in Aperture from camera, but import them before in a folder. I keep my shots in a folder hierarchy like YEAR/YYYY-MM-DD-SESSION NAME. Since I like to geotag my pics, I put a gpx file right in the same folder.
- Once they are on my laptop or desktop, I quickly review them right in the Finder: I set bigger previews, and trash most obvious bad shots. Usually this take no more than 1-2 mins. Don't care to be accurate, I just want to put away really bad shots, and have a "fell" of what I got in that session. At the same time, if I see some pic I'm sure I want to share later, I label it with a color. Such labels will be later imported in Aperture.
- Sometimes I even open all the images in Preview.app (Cmd-A, Cmd-O) and skim them there, and trash those I really don't like. This may take 5 mins.
- After that I use GPSPhotoLinker to automatically geotag pics from my gpx track, and optionally shift time of shot if needed (I usually sync my camera clock once in a while, so usually don't need to change anything here). If some pictures can't be tagged from a gpx track (mostly because I forgot to record a track), I use GeoNamesTagger to manually geotag them. This usually takes me a couple of minutes.
- Now I import them in Aperture, using File -> Import -> Folders as Projects. At this time, they will already be geotagged, and some of them may already have some color label. And I shouldn't have any really really bad shot in my library. I also add a description to the project info screen.
- Now I use the "batch change" tool to add generic keyword and captions to all the shot of the same subject, trying to don't leave any shot without at least a keyword. In the meanwhile, Aperture will search for faces that I'll tag later.
- Next I look at the previews, and stack together almost identical shots, mostly because taken bracketing or in burst mode. Close all the stacks, so I have an idea of what I REALLY pictured, not caring of different versions of the same picture.
- Now more time consuming work: I look at each shot/stack in the "split view", and rate every shot. I reject bad ones using "9" key, while I give 3 stars to god but not excellent shots, 5 stars to best ones and 1 star to shots I may trash later. Obviously I use also intermediate ratings. I'm ignoring shots inside stacks, unless I'm going to reject a stack: before rejecting it, I look inside it to see if there are some keepers or not. At the same time, I add color labels to the shots, to mark for example those I promised to give to a friend. This may take a quite long time, especially if you are experimenting and don't have a precise idea of what you want from that session. This usually takes half an hour to an hour.
- After that, I start again, reviewing my previous ratings: maybe that 3 stars photo was worth 4 stars, or shouldn't be a keeper at all. At this time I end rejecting even more shots. At this time almost all my shots are technically good, so I choose only bolder and more relevant ones. They should tell a story, and anyone should be able to "read" it. This usually is more difficult.
- Lastly, I use the search function to review shots with less than 3 stars, and decide to keep them or not. After that, I give a last look at my rejected shots before trashing them. Sometimes I decide to keep some bad shots and add some caption to them to remember me of the errors I did when I took them. This usually don't take more than 10-20 mins.
- Now I look inside each stack, and try to decide which shot to keep, and which one to trash, looking at them side by side. This may need a lot time consuming if you shot a lot in burst mode, or do a lot of bracketing.
- Now that I have a lot less shots, I start adding them more descriptive keywords and captions if needed. Usually I add more info to best shots, add faces, and fine-tune ratings.
- Only after rating, trashing and key-wording everything I adjust some shots, mostly to crop, straighten and enhance contrast, colors, saturation and exposure. I usually prefer shot better images than editing them in post, so I usually do very little changes in this moment, but you may have different tastes. I select and trash different versions of the adjusted image using the same approach described above.
- I review again my best shots, and flag or add a specific keyword to those I'm going to export for print or put on flickr. I usually export flagged shots to the original folder, so I can take it and use it right from the finder, without the need to open Aperture.
It takes few iterations to select best shots, the point is to be ruthless and cruel on yourself.
Having too many shots imho it's worst than not having any shot. Neither you nor anyone else wants to skim so many images, and great shots can be lost among so many mean images.
So we want to keep only great, unforgettable or clearly documenting something shots, and get rid of all that "noise". Three versions of the same shot don't add nothing to it, they are just mess.