Technical diving is not something you jump into. Whether your interests lie in nitrox, rebreathers, mixed gas, deep, wreck or cave diving, there is a lot of training involved.
Make sure to get certified by a professional organization with experienced instructors on staff. There are several organizations that offer certification like Technical Diving International and the International Association of Nitrox and Technical Divers.
Certification starts with the entry level Nitrox course. Courses instruct the student in the benefits, hazards and proper procedures for using Nitrox mixes ranging from 20% to 40% in qxygen content.
Divers can then move on to Advanced Nitrox. The object of this course is to train divers in the proper use of EAN 21 through 100% (oxygen) for dives not requiring staged decompression.
This course provides the training and experience required to competently utilize air for dives up to 180 fsw/55msw that require staged decompression, utilizing nitrox mixtures and oxygen during decompression. The Extended Range course provides the training and experience required to competently utilize air for dives up to 180 ft/55m that require staged decompression, utilizing nitrox mixtures and oxygen during decompression.
Next you can progress to Entry Level Trimix level which offers the training required to competenly and safely utilize breathing gasses containing helium for dives that require staged decompression, utilizing nitrox and/or oxygen mixtures during decompression to a maximum depth of 200ft/60m.
Advanced Level Trimix is for dives to a maximum depth of 300ft/100m.
You can get certified in wreck, cave and rebreather diving and learn how to combine them with your mixed gasses techniques. Like with every sport, proper training is everything.