Posting this here for Sang, this is the list of tools/texts I use for working on Classical Chinese texts:
An Introduction To Literary Chinese by Michael A. Fuller - This is an introductory textbook aimed at students wishing to learn Classical Chinese. Short of actual classes, which may not be feasible, this is the place I would encourage someone to start. When I first started working with 3K texts I was getting nowhere fast, and that's because I was trying to translate into English before I even knew how to read and understand the language itself. This book got me back on a solid path.
Outline of Classical Chinese Grammar by Edwin G Pulleyblank. This is not a textbook, but a reference book. I will use it to look up constructions and phrases when I am stuck and I also would read the sections that were related to whatever lesson I was working on in the Fuller book. Both books can probably be gotten less expensively used at other sites, but I've linked to Amazon because it's easiest.
New Age Chinese-English Dictionary - Pricey but worth it. Recommended to me by Lady Wu and it has served me well. There is an updated, 2008 edition - it is even more expensive though, and I haven't gotten it yet. The link above is for the 2001 edition.
SGZ - This is a paper copy of the SGZ and if you are going to work on translating anything from it, you are going to want to have a hard copy. If nothing else, it makes comprehending proper names and such a million times easier - without it, you have to get those things through context and that is a frustrating proposition. Only downside is the website is in Chinese. You also will want this for possible textual inaccuracies in online texts - just today I found where an online text erroneously had 王 - king, instead of the correct 壬, which is the 9th heavenly stem (part of the Chinese calender system).
Online text of the SGZ in Traditional characters - It can also be very useful to have an online copy of the text to work from. This is not the one I use - it went away a long time ago, and I've carried my saved .html from PC to PC over the years - but it looks ok to me. Pei Songzhi's notes are done as links to another page, which is interesting.
Online text of the SGZ in Simplified characters - Useful primarily because the dictionary above is organized by Simplified characters (although it also gives the Traditional forms). Again, not the one I use - it, too, is long gone - but looks ok.
MDBG Online Dictionary - Most of the time, for convenience, I work from an online/.html text. The pluses to this are that the text is laid out left-to-right and top-to-bottom, like an English text, as opposed to the top-to-bottom, right-to-left organization of a standard text. The easiest way to use an online text - at least until you start getting your vocabulary down - is using a tool like MDBG. You can annotate a block of text and it will give you the pinyin and some definitions, as well as doing things like radical identification. This is also useful for making paper dictionary lookup easier, since they are organized by radical and pinyin - and you will be consulting the paper dictionary a lot. MDGB is useful but it isn't everything.
Additional tools that I use but that aren't strictly necessary include Kingsoft Powerword, which is a more robust version of the MDGB service, kind of like a software version of the paper dictionary above. The downside is that it is about $75 and right now Google Chrome gives me warnings about their North American purchase site. However, it gives a lot of usages and has a lot of archaic and literary usages.
I also keep a copy of Rafe de Crespigny's To Establish Peace around because it contains an excellent article on military organisation at the time of 3K as well as an excellent glossary at the back. The text is available online at his website, but doesn't contain characters, which makes identifying various titles and ranks difficult. His website is useful for the article on the civil administration of the time as well, though again it lacks characters. I also have a copy of Achilles Fang's Chronicle of the Three Kingdoms that I sometimes consult. Both works contain a lot of notes by de Crespigny and Fang and since Sima Guang used SGZ as a source, sometimes these notes can help with a passage.
Adrian