I'm not aware of a tool but I'll give my tips.
- Strip the jacket 2-3 inches back. Jacket strip tools are great for this: a knife works but it takes longer and you're more likely to nick a wire (= start over) or accidentally cut yourself.
If you're using a boot, install it now.
Splay the wires out, unwinding them, and start lining them up in order as you go. Try not to unwind any further back than you've stripped the jacket. Hold them tightly and flat with one hand while you do this.
Keep holding the wires flat, but with your other hand, flex them back and forth a bit to get them 'seated' (to relax in this position). The idea is when you let go, they'll stay lined up and barely move (but don't let go until you cut them). This is much easier when you're using solid conductor cables (mainly in-wall type cables) as opposed to stranded conductor (used for patch cables).
Use a pair of side cutters to trim the wires to the correct length, about 1/2". Do this in a single cut, and make sure it's a straight cut so all the wires are the same length.
Push the wires into the connector. This is basically the first time you let go since lining them up. You want the wires to go to the very end (red arrow), and the jacket to be seated underneath the block that crimps down onto it (blue arrow).
If the jacket is cut too far back, the connector won't crimp onto it, and the only thing holding the connector on will be the wire connections. While it might work for a bit, these wires are easy to break, sometimes in a non-obvious way because only a single wire fails.
- Use a tester to verify it's good. The ones with indicators on both ends can be had for tens of dollars. It's much easier to fix if you find out it's wrong immediately, plus it helps teaches immediately what you're doing wrong.
Another tip: don't crimp them if you can help it! :)
Punchdown blocks on patch panels and keystone jacks are easier to do properly (especially for cat 6), and can make a nicer installation.
Patch cables (any short-ish run that doesn't go through the wall) are cheaper to buy assembled than you can buy the parts for (even with bulk cable and connectors and valuing your time at $0/hr), and the cables are better than what you can do by hand. Since stranded cable is also harder to assemble, avoiding assembling patch cables means you avoid stranded cables.
That said, many years ago in the late 1990s I spent an evening watching TV and creating a couple dozen ~1.5' patch cables for my dad's office network, and that was a pretty good crash course. Since then I've rarely screwed one up. :)
Really, it's just practice. For example, I'm a non-pro, doing a few cables/ends here and there, and every few years it seems I do a bigger job like networking a house, but then I go months between doing anything. I can crimp an end in under a minute for sure, and faster as I get back into the swing of it.