I usually just crank them tight, then back off a 1/4 turn or so, kind of like setting a wheel bearing, loose, but not too loose.
I usually like to adjust them with the section fully extended, then use a string line or eyeball each section to be straight with the base section. Do that one section at a time with the boom down flat, then stick out all your sections with the boom up, and if you get behind the boom, you can eyeball and see how you did.
If you are off with a section, you can see which section is off usually by getting behind the boom with it up at 65 deg or so. A little off on section #1 will be really off by the tip, and that affects chart, you essentially have the crane in a constant side load. It needs to be straight.