A manual for writers of research papers, theses, and dissertations, 7th edition - Kate L. Turabian 2007

Choose the right word
Revising sentences
Part I. Research and writing: from planning to production

Another bit of standard advice is Choose the right word:

1. Choose the word with the right meaning. Affect doesn't mean effect; elicit doesn't mean illicit. Many handbooks list commonly confused words. If you're an inexperienced writer, invest in one.

2. Choose the word with the right level of usage. If you draft quickly, you risk choosing words that might mean roughly what you think they do, but are too casual for a research report. Someone can criticize another writer or knock him; a risk can seem frightening or scary. Those pairs have similar meanings, but most readers judge the second to be a bit loose.

On the other hand, if you try too hard to sound like a real “academic,” you risk using words that are too formal. You can think or cogitate, drink or imbibe. Those pairs are close in meaning, but the second in each is too fancy for a report written in ordinary English. Whenever you're tempted to use a word that you think is especially fine, look for a more familiar one.

The obvious advice is to look up words you're not sure of. But they're not the problem; the problem is the ones you are sure of. Worse, no dictionary tells you that a word like visage or perambulate is too fancy for just about any context. The short-term solution is to ask someone to read your report before you turn it in (but be cautious before accepting too many suggestions; see 7.10). The long-term solution is to read a lot, write a lot, endure a lot of criticism, and learn from it.