The first Inf reset doesn't feel like much at first, but don't overlook Auto-Tree, it's a huge time saver. You also get infinity points, which let you spend stacked points to upgrade one(eventually more) skills past their natural cap. It's expensive and not something you'll really use till later but eventually using this will become necessary.
Every Infinity reset you perform after this unlocks something new. Usually it's just an expansion on an already unlocked event: Auto-Ascension and new perks, Auto-Rebirth, increased mutagen gain, new space tier, etc. After that you'll unlock Singularities, which are their own separate animal but give you really useful benefits.
At this point you should be ready to venture to new Dimensions. Note that traveling to a new dimension resets the one you were in, so don't click one by accident if you're close to finishing a reset! You can travel freely between Dimensions that you've unlocked, so you're never trapped. Each dimension gives a reward per tier level finished and a much more powerful one for fully completing it. These rewards may seem small at times but are absolutely game changing.
Hope this helps a bit, feel free to ask more specific questions if you have them. Cheers