Work on buoyancy and trim, buoyancy and trim, and buoyancy and trim 1st
Ranier makes a very good point about depth, a shallow pool or quarry will give you more bang for your buck in terms of buoyancy shifts, if you can hover just off the bottom while moving around, starting and stopping in 3' of water without breaching the surface you are off to a good start. Keep working on the helicopter turns, backwards swimming, and trim. Make that conscious effort to keep trim good- nipples and knees in the same plane, legs bent 90 degrees at all times.
Work on getting really comfortable with the basics, mask removal and replacement, donating your primary reg and re-stowing the hose (long hose), shutting down valves, et cetera- all while keeping your hover and not floating upwards.
Once you get that down start task loading- the main thing in any form of technical diving is that the basics become 2nd nature and you can focus on more complex problems. Make a conscious effort to have good gas management - you should know your SAC rates, and being conscious of your BT/depth at all times be able to guesstimate pressure to within a couple hundred PSI every time you glance at your gauge. All the while keeping good form and never touching the bottom- remember that all underwater operations in any form of diving can, and should be performed while hovering, there is never ANY excuse for kneeling on the bottom like an open water instructor
Once you get pretty proficient in all that, start doing some additional task loading- reel work, run a line, deploy a SMB with a spool, be able to work a reel while using a compass, et cetera. The main thing is to just keep diving , gaining that experience, and making that conscious effort to keep your form, display good buoyancy, and stay acutely aware of your gas management until it all becomes second nature.
Good luck!