As an inflatee of around a decade, I've only known of one person who injured themselves inflating (breaking a ri

. I honestly would love to hear people talk more about injury caused, as people often speculate that people get hurt (but hardly any direct accounts of this). Beside that, you'd feel pain far before causing any lasting injury (unless you use something silly powerful like a compressor or tire pump). Often anxiety can lead to people stopping, moreso than any injury. The worst I've felt was a momentary tearing sensation when inflating at capacity. That was skin tearing, as I otherwise lived to tell the tale.
But with that said, alongside frequent practice (even bloating can be a way of increasing capacity), I'd say using a low powered pump or something that works slowly will help combat cramps. Some people have used perisaltic dosing pumps, but a low powered aquarium pump or a cuff pump would work fine.
If there's any advice I'd give, it would be to set aside time for aftercare. Inflating can be exhausting, so it's important to dedicate a window afterwards for a shower or some snack. You'll feel super hungry after Inflating, so soup or something filling is your friend.
Lastly, avoid bloating with caffeine. Often if you are bloating to capacity and feeling anxious, heart palpitations will heighten panic big time. So much so that the body might get really stressed, making it much harder to get back into bloating. Caffeine free options or tea is a good pick for bloats, imo.