Avoid noun ings
It is not only the use of continuous tenses which makes reading harder. Words which end in ing are harder in themselves to read. Sometimes, it is awkward to avoid them. For instance, nouns like feelings and meetings may be difficult to replace, but even with these, you can sometimes get around them. Instead of What are your feelings about… you can say How do you feel about…. And instead of When is your meeting with… you can say When do you meet with…. Many of us have developed a habit of using nouns ending in ing, when a verb is shorter and neater. So, we might have said You can work on teaching the parrot to speak. Instead, you can say, You can teach the parrot to speak. It is shorter and less clumsy.

Using numbers
When you need to use numbers, they are easier as numerals than as written words, until they reach high numbers. So, write 8 instead of eight, even though that is not what you were taught at school (another convention). Counting up zeros, however, and manipulating them into words when they involve hundreds, thousands or millions is a complex task that often creates difficulties. So, say eight thousand rather than 8,000. I agree this is a contradiction, but oh well. If you spell out the number and then add it in brackets as a numeral, as they do in legal documents, readers usually will read the number twice. So, I have ten (10) eggs, will be read as I have ten ten eggs. I usually avoid the repetition.

Avoid percentages
Percentages too are difficult. I have found it possible to use terms such as half and quarter, but much beyond that becomes too abstract. Ninety per cent or 90% means nothing to many readers. Using rows of little stick figures with nine black and one white can sometimes be used, but be prepared to find that while the reader understands that the nine figures represent one thing and the one white figure is different, this does not translate into 90 out of 100, or 90%. These little stick people are interpreted in a literal fashion. Pie charts have limited usefulness unless they are carefully explained and kept simple. Column or row graphs are no use at all.

After the simplest one-half or one-quarter, I usually will say many, most of, hardly any, only a few. Of course, this is not as accurate as giving a percentage, but at least the readers get an idea, which is more than they are likely to get if you use more accurate terms. You lose accuracy but gain better comprehension. Again, it is a compromise.

Avoid foreign terms
Try to avoid using foreign terms if at all possible. E.g., for instance. Most people will look at e.g. and ask how it can mean for example. It is an abbreviation for the Latin term exempli gratia. Why not say such as or like? I.e. is another one, standing for id est, and meaning that is. So, just use the English. Vice versa means conversely; versus means against; RSVP stands for répondez s’il vous plaît and means please reply. There is usually a perfectly adequate English expression for what you want to say.