Yes. The apostrophe is a letter in Klingon just like t or a.
ro and ro' are two different words in Klingon, for example.
You cannot leave apostrophes out.
Note, Klingon does not use " (double quote) -- but you may see double apostrophes '' just as you may see other double letters, e.g. maw''a' with double apostrophe like juppu' or qettaH with double p/t. So be careful to spell such words not m-a-w-"-a-' but m-a-w-'-'-a-'.
The apostrophe stands for the glottal stop -- the sound most English speakers make automatically before a word starting with a vowel.
Some English speakers also turn /t/ into a glottal stop; if you can imagine how a Cockney speaker might say "bottle" as "bo'l", or "bit" as bi', that might help.
What kind of "facilitating trick" are you thinking of?
Also, are you reading all the tips and notes before starting a new unit? These try to explain any new grammar introduced in that unit.
If you're using the website and already have the "crowns" feature, you'll have to click on the lightbulb rather than on "start" in order to see the tips and notes.
If you're using a mobile app rather than the website, you may not have access to the tips and notes. My personal recommendation: don't use the Duolingo mobile app to learn Klingon.
I didn't think tlhIngon Hol was available on the mobile app yet. I can't see it.
But yeah, you can still use the app to review and strengthen, if it more convenient for you. But start new skills on the web client where you can see the learning briefings first.
Also , keep in mind if this language is frustrating and seems random, that it is specifically an alien langauge, so it will be as far as possible from any Terran languages you are most familiar with. It isn't supposed to be like French, Spanish or German which have common roots with English. So by it's very nature it will be much more difficult.
I was getting the Tips on Chrome for Android up until last weekend (about 15 June 2018), and then they did some kind of upgrade, and they've all disappeared now. That's across all languages, not just Klingon. It's very frustrating. I'll try to go to my PC before starting each new Klingon lesson to review the Tips section, but it's not always convenient. I hope they'll bring the Tips back to mobile at some point, even if it's only on Chrome and not on the app.
In this sentence, it's a capital i. If you look closely, you can see the curl on the bottom of the l which is absent from the I. I'll also give you two helpful rules. 1) Two vowels cannot be adjacent. 2) Every consonant has to have at least one vowel adjacent (remember that tlh is a single consonant). Using those rules you can see that there must be an I next to the H.