One of those mistakes is bringing to many presuppositions to the text. To be clear about this, there will always be presuppositions. That is unavoidable. The secret is to allow our presuppositions to be conformed to the text. For instance, suppose I read a passage from the historical narrative of Acts. Acts is a historical document which I believe to be a faithful and true to the events listed therein. Now suppose I read these verses:
But Paul and Barnabas remained in Antioch, teaching and preaching the word of the Lord, with many others also. And after some days Paul said to Barnabas, "Let us return and visit the brothers in every city where we proclaimed the word of the Lord, and see how they are." Now Barnabas wanted to take with them John called Mark. But Paul thought best not to take with them one who had withdrawn from them in Pamphylia and had not gone with them to the work. And there arose a sharp disagreement, so that they separated from each other. Barnabas took Mark with him and sailed away to Cyprus, but Paul chose Silas and departed, having been commended by the brothers to the grace of the Lord. And he went through Syria and Cilicia, strengthening the churches. (Act 15:35-41)One thing about this passage is that it doesn't tell us who is right or wrong. It tells us that Barnabas and Paul had a disagreement. Now the person who has been reading Acts and knows that Paul is an Apostle may automatically assume that Barnabas is in the wrong. On the other hand, a skilled interpreter of Scripture may come to the conclusion that Paul was wrong, based on his knowledge of other Scriptures. The truth, however, is that the Bible does not say who is right or who is wrong in this instance. Presupposing that either Barnabas or Paul are wrong in this instance takes our focus off of the point of the text which is that Barnabas and Paul went their separate ways as God was leading each of them to do.
Another mistake in Bible Study is digging to deep. What I mean by this is that a person can immerse himself so deep in the words and what the words by themselves mean that he loses sight of what the passage, which is made up of words, actually says. Martyn Lloyd-Jones was a marvelous expository preacher in the sense that he preached verse by verse through the Bible. And be it far from me to criticize someone who has had such an impact on many well-respected Bible teachers in our generation. IL have never heard a sermon by Lloyd-Jones that I did not agree at least ninety-eight percent of the time theologically. But I sometimes wonder if Dr. Lloyd-Jones went to deep to the point of missing the point of the passage.
Another example is a sermon I heard preached on the heart once. I don't remember the passage or the preacher, but I do remember that he neglected the text in order to explain how the human organ that is called the heart works. I also remember that the passage was not referring to the physical heart, but the seat of emotions. Not only did this preacher miss the point of the passage he was trying to preach, he missed the point of the word that he neglected the passage in order to preach! This is what can happen when we become to involved with word studies. We become so focused on one or two words in the passage that we miss what all the words together are saying.
Word studies are important. But only when they are used to shine light on the whole passage of Scripture we are seeking to understand.
Another mistake to avoid is depreciating the English text. I would venture to say that the English translations that are available today are the some of the most accurate translations in the history of the Western Church. Of course the Greek and Hebrew texts always take precedence over the translations, but there is no need to doubt what the English says clearly and unequivocally. If the verse makes perfect sense to you in its context, leave it alone. It probably means what it says. And the translators know more Greek and Hebrew than most of the rest of us. You may not like what the verse says, but let it say what it says. Confirm what it says by researching it, but do not change it just because it is not palatable to you or your system of theology. Conform yourself and your theology to Scripture.
A fourth mistake is not interpreting Scripture in the light of 2,000 years of church history. In the course of church history, thousands of Bible interpreters have wrestled with the same texts you do. It is never wise to impose your view of the consensus of trusted Bible interpreters throughout the centuries without a very good argument.
There are times that the consensus of church history has been wrong. I am a Baptist. I am Baptist because of theological and scriptural reasons. And by being a Baptist I realize that most of the biblical interpreters from 300 A. D. to 1700 A. D. are opposed to my view of baptism.
I say this to clarify my meaning when I say "It is never wise to impose your view of the consensus of trusted Bible interpreters throughout the centuries without a very good argument." I have weighed the arguments from both sides and landed squarely on the Baptist side.
Finally, don't work outside of a proper framework. Dispensationalism, Progressive Dispensationalism, Covenantal Theology, and New Covenant Theology all have their downsides. Even with those downsides your interpretation of Scripture will probably fall into one of those categories. Don't be bound by the framework you find yourself in, but recognize that these frameworks can help you interpret Scripture. Use them as tools for interpreting Scripture, but don't bow the knee to them.
Creeds and confessions of faith from history are also helpful for Biblical study. In these we have a good source for finding out what the Church from it's very beginning has believed. Use the Apostle's Creed to give you an overview of the message of the New Testament. Use the Nicene and Athanasian Creeds to understand the various Trinitarian patterns found in Scripture.
Most importantly, don't interpret Scripture outside of the framework of a local church. We are put together in local congregations for many reasons. One reason is so that we may study the Scriptures together as we grow in the faith together. Your Pastors, Sunday School Teachers, and even the janitor can be a source of encouragement and help as you wrestle with God's Words. And you can help them as well.