The IB is not harder than other curricula. It is differently hard. Here are three things I would tell my DP1 self, in order of how much stress they would have saved me.
1. The IAs are graded more leniently than you think, but only if they are on time
Internal Assessments are not secondary. They are 20 to 30 percent of your grade depending on the subject. But the marking is fair and the mark scheme is explicit. The thing that costs people marks is leaving the IA until late, panicking, and submitting something rushed. Start earlier than you think you need to.
2. TOK and EE are gateway grades, not extras
Not submitting TOK or EE means failing the whole diploma. Students treat them as throwaway through DP1 and then find themselves in a crunch they did not plan for. Block two to three hours a week for them from DP1 term 1. That sounds like a lot. It is a lot. It still works out to less than the crunch does.
3. Your Extended Essay supervisor is the single most important relationship in the programme
Not your subject tutors. Not your school counsellor. Your EE supervisor. Pick them carefully, meet them regularly, and take their advice seriously even when it slows you down. An EE that gets an A moves the needle on your total points more than any single subject's last exam.
Bonus: the first six weeks set the tempo
If you learn to write subject-specific answers, maintain a mistakes book, and block time for IAs and EE in the first six weeks of DP1, the rest of the programme runs on momentum. If you skip those things, every month gets harder.