When I was on dial-up I did the following:
1. Disable images and then create a white list for the few sites where I wanted images.
2. Disable JavaScript and then create a white list for the few sites where I wanted JavaScript.
3. Disable Java. Period.
4. Add entries to the /etc/host for the most used sites. Using dnsmasq helps wonderfully because a second hosts file is supported as well as DNS name caching. I can populate this second hosts file with a ton of ad blocking URLs, which further reduces traffic.
5. For a while I used squid and ran my web browser through that proxy port. This might help if you have the disk space.
6. Use an alternate file downloader such as KGet rather than using the browser. If possible, schedule downloads for a later time when not surfing because the downloaders are bandwidth hogs.
7. If using Firefox, use NoScript to block Flash, iframes, etc.
If you are after information then disabling most of the fluff will help. If you are seeking a "web experience" then disabling these features will be frustrating, but so will running on dial-up.
If you want to be real hard-core, consider a text-based web browser such as Links or Lynx.