If I were to suggest 'gems' that I've found over the years, I'd suggest this.

"How to Read the Bible for All Its Worth" by Gordon Fee
(Biggest takeaway; Scriptures were written by a certain people, within a certain culture, using a certain language, with relationships we may/may not know more about, based in a time when other comparative documents were written. So, Scripture is a bit more deep than 'Go take up your mat and walk'.)

When it comes to translations, by order of study:
NASB, AMP, NLT, MEV, MSG.

http://openbible.info - for quick word studies

http://blueletterbible.org - for greek/hebrew

http://biblehub.com - for Treasury of Scripture of Knowledge (This is when I'm going ALL IN on a study. Each scripture verse has corresponding parallels. The similar verses can help dig out a gem on studies.)

Plus, when I'm using Treasury of Scripture of Knowledge, I read a dozen or so various commentaries. Sometimes even 'no named' people because sometimes you find cultural references that you'd never find elsewhere.

Finally, I like the web. Physical books is just time consuming. Flip to this reference, flip to that reference. Also, I type fairly fast. So, being able to do research as fast as I can think, is very very nice.