A lot more power variations exist that haven't really been mastered by anyone, as you can generate endless amount of 'power tricks' by mix and match fl around and/or topspin variations.
Playlist of my power clips and tutorial and slow motion clips
In watching these videos, other people's tutorials and your own practice, you should pay attention to: COP position relative to fingers and pen's angle of rotation. Consistency, control and higher personal record are basically the same (improving one will improve the others).
Preferably, you should get a COP marked mod (easier to track pen's movement visually) that is easily visible over your background; length more important than excess weight - 21.5-23cm 16-20g would be good for people with 17-20cm hand length.
In doing fl, you can consider tricks/short sequences as 'highlights' (harder), and 'filler' (easier material to extend length, maintain and regain control).
^Old video of some simpler power trick sequences, part 2 here.
Learning order:
If you are aiming to make decent length (10-15 second) fl sequence as your main focus, then your priority should be:
1. fl ta rel (i.e. fl ta ~ index spread to air) - the most important filler trick to extend length of fl combo, used to recover control if you mess up previous trick or highlight material. If you master fl ta rel, it is easier to do 10 [fl ta - ss] aerial than 10 [fl ta - ss] cont without aerial, so fl ta rel is very useful. fl ta rel without using index cannot really be used for regaining control, so it's recommended to learn fl ta ~ index spread to air method.
2. mid and pinky spread - filler material, and for linking into slightly harder tricks (like spread - fl ta - palmspin or spread - fl ta - spiderspin).
3. 1+2 - Once you can do x 5-10 fl ta rel and mid/pinky spread, practice doing spread sequences with fl ta rel in between the spreads at various intervals (e.g. [fl ta rel - pinky spread] cont)
4. After 1-3, add aerial hai tua, [fl ta - palmspin] as highlights; with fl ta rel+spreads as filler for control and length. [spread - handbust - spread] is also useful; you should also learn fl ta cont and index bust cont at this point.
5. After you have learnt tricks and sequences described in 1-4, you can spend more time on harder variations. Generally, linking with hai tua is harder than similar linking with aerial hai tua, which is harder than similar linking with spread, (e.g. hai tua - fl ta palmspin harder than aerial hai tua - fl ta palmspin which is harder than spread - fl ta palmspin).
Example of short sequence with tricks listed in 1-4:
Note: hai tua is not as useful when learning to make fl sequences, as hai tua is more of a highlight linking due to its difficulty (e.g. [fl ta - palmspin - hai tua] cont is far harder than any spread/aerial hai tua sequences). Learning aerial hai tua - hai tua is recommended as it gives a pretty nice visual effect and ending feeling.
If you are aiming to make a condensed strong finisher, your learning priority will be different. For example, you can ignore 'logical progression', and skip learning spreads or fl ta rel, because spreads/fl ta rel will not directly help in making a short condensed hard sequence; instead you might choose to train pun kan, hai tua and [pun kan - hai tua] cont.
Rough difficulty grouping
Easy - for beginners, got to start somewhere: fl ta rel, fl ta, spreads, index bust, fl ta, powerpass; fl ta rel and spread sequences, powerpass and spread sequences
Normal - for most spinners: fl ta - palmspin, index bust aerial, mid bust, aerial hai tua, hai tua; spread and handbust sequences, aerial hai tua - hai tua, fl ta rel - fl ta palmspin, powerpass - palmspin
Hard - for those who do fl a fair bit: index pun new, fl ta - spiderspin, pun kan, ring bust cont, hand bust cont, [fl ta - palmspin 1.0] cont; [aerial hai tua - fl ta palmspin], [hai tua - fl ta palmspin], fl ta rel - fl ta spiderspin, index pun new aerial
Lunatic - for people who are a little crazy: fl ta - ring spiderspin, fl ia - spiderspin, mid/ring/pinky pun new, [fl ta - ss 1.0], [fl ta - palmspin 1.5/2.0] cont, aerial hai tua/hai tua - hard category trick (e.g. [aerial hai tua - index pun new aerial] cont; fl ta spiderspin - hai tua - fl ta spiderspin, [pun kan - hai tua] cont etc).
Extra - give up now, what are you doing to yourself?: fl ma - ring ss, mirr pp rev - ring ss, special variation aerial of fl ia ss/fl ma ring ss/mirr pp rev ring ss, [fl ia - ss 1.0/1.5/2.0]; [fl ma ring ss/mirr pp rev ring ss - hai tua] cont, [pun kan - spiderspin] cont, fl ra - pinky ss, pun kan 1.5......
??? - [unexplored level?] for things currently possible only in imagination. Of course, I intend to change that eventually.
Further discussion
Spinnerpeem established that ultimate aim of power tricking mastery is to give sense of stability - the impression that you are in total control of the mod and that even if you filmed x 200 of the trick, audience gets the feeling that you can do far more (even if x 200 is your personal record).
For some trick variations, skill in one variation translates quite well to other variations (e.g. mastering index bust helps mid bust; index pun new helps mid/ring/pinky pun new; fl ta - ring spiderspin helps fl ta - index, mid or pinky spiderspin). However, there are some places where you might expect previous skill helps where it does not (e.g. fl ta ss mastery does not help fl ia ss, fl ia ss does not help fl ma ring ss, fl ta palmspin does not help index pun new - I talked to ppm [TWPS] and he thinks same as me for these tricks).
For adding extra rotations, I've concluded that for palmspin fl ta and index pun new: making the palmspin 1.0 rotations instead of 0.5 gives 4-5x cut in record number (x 251 vs x 51 for palmspin fl ta; x 120-150 vs x 25-30 for index pun new).
For spiderspins, the difference will be larger because there is less room for error as spiderspin literally has less physical area to be done on than palmspins, so difference is about 10x cut. (200 vs 22 for fl ta ss; 202 vs 20 for fl ia ss). For ring ss variations, the difference is greater than 10x.
Adding rotations to aerial portion has a smaller change in difficulty (for my variation that doesn't use thumb in doing aerial for fl ia ss, fl ma ring ss and mirr pp rev ring ss, below), I estimate the difference in 0.5 rotation aerial and 1.0 rotation aerial is roughly 2x.
Of course, you can do something like [fl ia - ss 1.0] aerial 1.0 which would raise difficulty by enormous amount (especially because the worsened control from the higher aerial will greatly impair ability to enter into the extra rotation spiderspin after it, and vice versa).
The 'cheat method' of doing certain power tricks by using small aerial instead of topspin - pause windy's vid below at random intervals, and you will see mod entirely leaves hand - doesn't change difficulty much for usual fl ta palmspin or index pun new, but it reduces difficulty by a fair bit for spiderspin variations (and looks uglier unless you can control it perfectly at minimal amount like spinnerpeem does).
Some spinners choose to practice harder variations over simpler ones to raise the harder variations to higher numbers than the simpler ones - A13x disliked the appearance of his [fl ta - palmspin] cont, so he trained index pun new and [fl ta - ss] a lot. Spinnerpeem did not learn mid/ring/pinky spreads because he simply doesn't need to use them. I really like [fl ia - ss], [fl ma - ring ss] and [mirr pp rev - ring ss] so I trained them lots and lots, so my technique of [fl ia - ss] is better than my palmspin/pun new variations; and my [fl ta - ring ss] is far weaker than my [fl ma - ring ss] and [mirr pp rev - ring ss].
Some spinners choose to practice harder variations over simpler ones to raise the harder variations to higher numbers than the simpler ones - A13x disliked the appearance of his [fl ta - palmspin] cont, so he trained index pun new and [fl ta - ss] a lot. Spinnerpeem did not learn mid/ring/pinky spreads because he simply doesn't need to use them. I really like [fl ia - ss], [fl ma - ring ss] and [mirr pp rev - ring ss] so I trained them lots and lots, so my technique of [fl ia - ss] is better than my palmspin/pun new variations; and my [fl ta - ring ss] is far weaker than my [fl ma - ring ss] and [mirr pp rev - ring ss].
I apologise somewhat for the slight showing off in certain areas of this post, but I hope you learnt something from it ^^