Suggestions

1. Say what you did; do not give directions for doing it, as in a lab manual.
2. The past tense is best for describing what you did.
3. Use correct symbols, not spelled-out Greek letters, etc. Hand-write them if necessary.
4. All measurements should have errors and units. Exceptions are when the error is negligible, which should be commented upon, and, for example, the g-factor, which is dimensionless. The typical form for giving a measured value is: (3.5 ± 0.3)x10³ cm.
5. Give only as many significant figures as are consistent with the error on a value.
6. Poisson errors are only correct for counting quantities. In most fitting programs, the calculation of Poisson errors is only correct if the y-value is the actual count, not counts divided by time, or average count.
7. Generally, give data as a plot, not as a table of values. The data should be represented by points with error bars, while the theory or fitted function should be given as a curve. Axes should be labelled with the name of the quantity and the units, in parenthesis. "Time delay (ns)"
8. Don't usually refer to computers or computer programs. Refer to the method instead ("chi square fit", not "fits program" or "gnuplot").
9. Do not put too much detail (such as equipment descriptions) in the abstract.
10. Do not show the details of calculations in the report; put them in your lab book and give the final equation, value, etc. In other words, describe the calculation, but don't do it in the report.
11. The names of people used as units begin with a lower case letter if spelled out but are capitalized if abbreviated (newton, N).
12. Compare your results with the previously measured values (usually not "given" or "known") in terms of your calculated error. If a result differs from the previously measured value by twice the calculated error, we say it is off by 2 standard deviations or by 2 s.d. The difference will be more than 1 s.d. 32% of the time, but more than 2 s.d. only 5% of the time.
13. Abbreviations such as PMT should be explained the first time they are used and are usually given in capital letters. "photomultiplier tube (PMT) "
14. Try not to repeat the same word in a sentence or the same phrase in neighboring sentences. (Repetition cannot always be avoided in technical writing.)
15. Try to write consistently in the same "person". Either use first person (as in "We measured and recorded the time delay") or third person (as in "The time delay was measured and recorded"). Don't change between first and third person too frequently or without reason. Note that third person writing often requires passive "voice" as in the example above. It is common in technical writing.
16. Use single italic letters, possibly with subscripts, to represent variables used in your analysis. "We measured the separation of the counters, d_c." NOT "We measured the separation of the counters, dcounter." Units are written in the regular font (not italics): "d_c=7.5 cm."
17. Somewhere in the text you must refer to every figure by number.

(Extensively borrowed from Prof Mike Peters)