There's not always a lot you can do for this sort of thing, but I know a couple things that are known to help. So if you are using Firefox (which you kind of have to be for any of my tips to work) download the FasterFox addon. You can either Google search it or go to Firefox's addon site and search.
This one helps, I believe, a bit. That is to disable IPv6 in Firefox (IPv6 is the replacement for IPv4 when IPv4 runs out of possible IP Addresses from all the new computers popping up around the world but is not hardly used right now). In your Firefox address bar type "about:config" without the quotes. In the filter bar type "ipv6" and one result should be left. Double click it, network.dns.disableIPv6, so that its value is set to true.
The next does technically help but can throttle websites bandwidth just a bit if set too high. One again type "about:config" in Firefox's address bar. In the filter type "network.http.pipelining", or just type "pipelining" to get all the results we need to edit, and double click it so that it's value is True. Next type in "network.http.pipeling.maxrequests" and set it's value to about 4, which I believe is the default. In any case I wouldn't recommend anything higher than 8. Basically what this second edit does is change the amount of times Firefox demands the page to be loaded. I personally believe anything between 2 and 4 is quite fine. Finally type in "network.proxy.pipelining" and set its value to true.
So those are all types that will help if you're just browsing, with Firefox, and I'm not sure I know any general modifications to help your connection constantly... actually... well I haven't used it myself so this is more or a less a 'good luck buddy' sort of thing. But I believe SG TCP Optimizer is supposed to be a decent program to tweak your internet connection. You'd kinda have to just try and check to see if it helps or not.
Also as BearClaw said Adblock Plus is a great addon for firefox. It will save yourself a bit of bandwidth by blocking tons of ads.
Hope at least something I said will help. I remember what it's like having slow internet too =(