In principle I would recommend preaching expositionally rather than thematically. You chose a passage and expound what it conveys rather than starting with your own theme and finding support for it through different verses. Using the later can easily give a platform for soap-boxes and even false teaching.If you are a beginner – start with passages you love, understand are are pretty familiar with rather than attempting to tackle Revelation or Ezekiel.
Read that passage 5-10 times until you are as familiar as you can be. After that read it again underlining what ‘jumps’ at you.

Then ask these questions:

• INFORMATION – what does the passage say?
• REVELATION – what does that mean?
• APPLICATION – what does it mean for me/us?

You can use aids like commentaries (they will explain issues that are more complicated or technical), concordances and an atlas – but only after you have done the homework above. They are added extras rather than ‘copy and paste’ materials.

If you see the sermon as a sandwich (not sure what Spurgeon or Dr. Martyn Lloyd Jones would make of that) – the content will be in the middle, The start is the context and the end is the conclusion. The context is absolutely essential. It will always ensure that you understand what is happening around your text (before and after). The context will beg questions like: ‘who, when, where, why, what, to whom’.

The conclusion must be both practical and memorable. It would be great if you can make it as applicable to mundane issues as possible. If you can create a good catch-phrase or memorable illustration – that would be  a bonus.

Enough for now. Next I will be writing about prayer.