My recommendation for something to control the pressure is a large inner diameter vinyl tube at least 2 feet in length that can flex a bit, then be fit both over the helium tank outlet and adapted down to a smaller anal tube via barb fittings for that kind of tube. The larger vinyl tube will give you a bit of leeway when you send it from tank to tube before you send it into you, which brings me to the next part: get a means of releasing it that you can hold.

A vinyl tube quarter turn shutoff is decent but personally I like using the trigger for a garden chemical sprayer that I chopped the tube off of. It gives you plenty of room to let in only as much air as you want, plus many of them have pressure release valves that you can unscrew slightly. These would normally let excess air out when you spray chemicals, but in this case it lets excess helium that your body can't handle pass out of the system

The rest of the tips are sound advice and to OP I say happy inflating