I don't know your best options because you're based in Denmark, and I'm not familiar with what works best for your region. You may eventually make it to the U.S./Caribbean/Pacific coast of North/Central America & South America region. With that in mind:
1.) I don't recommend diving with tiger sharks until you work your way up.
2.) There are a number of places reef sharks and nurse sharks are fairly common. Jupiter and Key Largo (Florida), St. Croix (north coast), live-aboard diving out of Belize and the Caymans, and especially the Turks & Caicos.
3.) North Carolina has off-shore wrecks, some frequented by sand tiger sharks. Not shark feeding or baited.
4.) Jupiter, Florida - especially winter when the lemon sharks aggregate. You can do non-shark feed diving (e.g.: Jupiter Dive Center) or shark feed diving (Emerald Dive Charter).
5.) The Socorros region by live-aboard, which has a range of pelagics (not just sharks).
6.) Cocos Island by live-aboard.
7.) Galapagos by live-aboard.
8.) Shark Feed/Baited diving is a very contentious topic, with intelligent, reasoned arguments on both sides. Read up on the topic and make your own decision.
9.) Diving with Great Whites is usually done via shark cage. Guadalupe, Mexico is the main regional draw for that. It's done elsewhere in the world, too.
Not all of these (or most) would I recommend at 24 dives, but a look at the bigger picture may help you decide how to plan to build experience.
Here are some trip reports to help with places I've been.
Key Largo with Rainbow Reef Dive Center 2013 -
http://www.scubaboard.com/forums/fl...iving-key-largo-rainbow-reef-dive-center.html
Jupiter 2014 -
http://www.scubaboard.com/forums/florida-diving/491927-jupiter-trip-report-9-7-14-9-11-14-a.html
Morehead City, NC August 2015 -
http://www.scubaboard.com/forums/no...us-dive-center-aug-9-13-2015-trip-report.html
Emerald Charters Trip Report 2017 -
Emerald Dive Charters Trip Report
St. Croix Research Report Aug. 2017 -
St. Croix Research Report Aug. 2017
Sun Dancer 2 (Belize) May 2015 -
http://www.scubaboard.com/forums/li...ving-belize-via-sun-dancer-2-may-2nd-9th.html
Cayman Aggressor IV May 2016 -
http://www.scubaboard.com/community/threads/cayman-aggressor-iv-trip-may-2016.527640/
Turks & Caicos Aggressor II Report Apr. 2018 -
Turks & Caicos Aggressor II 4/21-4/28 Trip Report
Richard.