Long ago and far away I took some upper division university level math classes. Like Geometry in high school math, upper division university level math classes are interested in proving things. As we proved things we talked about what is necessary for proof and what is sufficient for proof. In chemistry, it takes hydrogen and oxygen to make water, they are necessary. It also takes intense heat, a spark is necessary. Together, they are sufficient. You can put hydrogen and oxygen together and nothing will happen. You can make a spark and nothing will happen. But if you make a spark in an atmosphere of hydrogen and oxygen you will get a big explosion and produce water vapor. A problem with much thinking in both science and religion is that people think about what is necessary but don’t think so much about what is sufficient. The parts of the plan of salvation are necessary. The Bible associates them with salvation, so I accept that they are necessary for salvation.
Is the plan of salvation sufficient? The Bible, it seems to me, doesn’t tell us what is sufficient. I might ask, are the parts of the plan of salvation the only things that the Bible associates with salvation? Well, no, it also says to stand firm to the end. That is a little vague isn’t it, what do I need to do to stand firm to the end? I could also ask, is there anything else in the Bible, the Bible is a big book, is there anything else in the Bible, something that is not explicitly associated with being saved, that I need to make it to heaven? So, that is my question, I want to make it to heaven, what is sufficient?
I understand the wording you are using and agree that this is a valid question. Still… I am not sure exactly what you want from me. The simple answer is that in order to make it to heaven, you need to be saved by the blood of Jesus and remain faithful until you die. If you have received the Holy Spirit as a “deposit, guaranteeing our salvation” (paraphrasing Ephesians 1), then, unless you fall away (a la Hebrews 6:4f, Hebrews 10:26f) then you will be in heaven. There is nothing you have to “do” to remain saved once you are saved. You simply must remain faithful to God–not blatantly turn your back on him after you are saved. The Book of Hebrews is full of advice on how you can assure that you will remain faithful. This is the purpose of the book, so I suggest you read it carefully and put the admonitions in the book into practice.
So, your question amounts to “What is necessary to be saved?” What is necessary to be saved is sufficient to make it to heaven, unless we turn our back on God. I assume you already know what is necessesary for salvation. The “work” has already been done by Jesus, of course, but in order to be saved, we need to accept the message (Jesus died for our sins, etc.), repent of our sins, make Jesus the Lord of our lives (not just in word, but in our hearts and minds) and be baptized in water in the name of Jesus for forgiveness of sins.
Although this is a hard thing for us to do, the plan is rather simple.