Frankly, I'm surprised that this was not more populated. This seems to a subject which many teachers, theologians, and preachers like to discuss. Maybe no one caught this since it's buried near the bottom of the forum.
That being said, let me be the first to suggest some Bible study tools for those either looking to add to their current toolbox or just starting out and don't know where to start.
I think it goes without saying that if you are here then you are probably using e-Sword or MySword as your Bible software of choice. Smart move. There are plenty others out there like Logos, Accordance, PC Study Bible, and Word Search (formerly Bible Explorer). However, e-Sword is free (can't beat that with a stick), has a great interface, is just as powerful as the pricey versions, and has plenty of add-ons that you can download and install to customize your Bible study experience with preferential precision. I have been using it exclusively for years and like we say in the slang vernacular, Rick Meyers killed it when he created it. God bless that man.
The first and most basic is a Strong's Concordance. This is a good way get a basic grasp on Greek and Hebrew word meanings.
Next to that is Vine's Expository Dictionary. This goes much more in depth to the meaning of the Greek in the New Testament and is a staple reference for the serious student of the New Testament. W.E. Vines attempted to create a similar reference for the Old Testament as well but it wasn't as in depth and he went to be with the Lord before he could finish it if memory serves right.
There are two Bible dictionaries I use. Either of these is fine. The first is Holman's Bible Dictionary. This comes complete with illustrations and photos of ancient sites as well as in depth definitions of particular people, places, and things throughout the scripture. A plethora of contemporary biblical scholars and professors have contributed to it. This is a top notch dictionary and I highly recommend it.
The other which is every bit as good as the Holman's Bible dictionary is the updated Unger's Bible Dictionary. This is the dictionary I began with early in my walk with the Lord and I keep a copy just to compare the two and have a full understanding of a particular subject I'm studying.
Maps are the next thing and the maps that come with e-Sword works just fine. Gotta be honest here. This is where Logos and Accordance shine. They have some impressive graphic packages, interactive maps (Logos), analytics and more.
Next are commentaries which are optional but helpful. It's like having your own personal Bible teacher which is why I recommend them. When I prepare to teach, I may consult anywhere from seven to ten commentaries after I've written my full notes on a verse. This is totally optional and you don't have to be anywhere near where I am in terms of number and two or three good ones are just fine. Matthew Henry (awesome but my boy writes a lot), JFB (just the opposite. Too short on many verses), and John Gill (just wordy for no good reason at times but still some good, solid material), which come with e-Sword, are just fine. I use all of them along with Adam Clarke, J.P. Lange, John Calvin, John MacArthur, William MacDonald, Warren Wiersbe, and John Wesley.
Commentaries may help you in comprehending a text. The only thing I suggest when utilizing them is to use them after you have extrapolated all that you can from the text. This ensures that you are actually doing the work and studying “to show thyself approved unto God, a workman that needeth not to be ashamed, rightly dividing the word of truth”.
One thing that you can do is sign up for Logos account and get their free offerings every month. It's a free library of some classic, orthodox teaching and is a great adjunct to have at your fingertips.
These are the basics with just some extras thrown in. There's more but this is plenty and will keep you very busy in your research and understanding of the Lord's Word.
There's my list. Who's next?