Unlike the TEC & Advent SBs, Orkies are used regularly in MP (because they can move). So, if you're playing Vasari, also try to SB the enemy's homeworld, just to get an idea how that's done vs. the [incompetent] AI and random noobs (you might meet online). You should have no trouble rushing a SB to Hard AI's homeworld in Tiny and Small Random maps. The more souped up AIs [Unfair+] might pose a bit more challenge because of their bigger fleets, depending where those fleets are at the time you initiate Orky deployment. Don't expect that to work vs. a semi-skilled player that uses at least 10-15 LFs to target your SB while it builds though. Alas, you can't expect the AI to try to pull that on you, so if want to practice defense vs. someone SBing your HW, you'll have to save the game and switch slots.

Another thing that you should (and can) practice vs. AI are aggressive early attacks glassing his outer colonies. You need to learn how low the hp on your capital ship can get before you need to turn tail and run back to a friendly repair platform. This of course depends on how big the enemy fleet pounding your cap is, how far the repair platform is, and the game speed settings. Normal vs. fast/faster ship movements in particular have a fair bit of impact on that.

Finally, a more advanced form of attack to practice is busting his planetary constructor ships (and some resource extractors) and leaving a delaying force in the well, which slows down the respawning of said constructors by an order of magnitude (300 vs. 30 seconds). Advanced players do use this rather important game mechanic (both in MP and SP) to resume attacking after regenerating health etc. in a nearby friendly system while denying the defender the opportunity to shore up his defensive structures in the meantime. Alas, the AI is extremely incompetent at targeting your planetary constructors, so you won't get much practice defending/saving them vs. the AI. Nor will you get the chance to practice how to clear out respawn-delaying forces quickly vs. the AI, because when it runs, it turns tail with his whole fleet.

The solution to that is to pause the game in your first few plays while you read in-game descriptions, the Wikia etc. You can also give orders while paused, though pausing is basically off limits in MP mainly for social reasons.

Since you like ES, which I find overbearing in the econ department, I'm going to share my Sins advanced econ tricks [which frankly pale in comparison with ES]. To play really well on the Sins econ front, you actually need to plan your next one or two expenditures and a spreadsheet can help with that in the beginning, before you develop an intuition for when you should (and when you shouldn't) buy/sell on the Black Market in order to make your next purchase (and sometimes the one after that) happen faster. I use[d] one that basically looks like this:

For example, in the above scenario I want to have enough to pay for the development of a planet I'm about to colonize and its first extractor. What I should do [to minimize the time before I have the funds] is to sell all my crystal right now. The above doesn't show the formulas, but they are trivial [exercise!]

In general [but there are exceptions], it's not worth buying resources after you have 1-2 moons/roids, you'll be typically selling from that point onward. If you find yourself wanting to buy resources, say to upgrade a planted sooner [say to avoid underveloplment tax], notice that you're also doing that [buying resources] with the underdevelopment tax itself, and for shorter periods of time [less than a minute] that is usually cheaper than buying a large chunk of resources at the exorbitant Black Market prices. (I also have a spreadsheet [part] for precisely calculating that for longer periods of time, but this rule of thumb is usually okay.) Another econ thing that's easy to tabulate and learn is how much population before the max is reached (at the current dev. level) you need to buy the next upgrade so that the population grown isn't temporarily stunned and you also don't waste credits/resources by buying the upgrades before they are needed. In MP, you won't have time to do this kind of stuff anywhere near optimally, unless you're in the eco slot and have lots of experience guesstimating the above. One econ gotcha to be aware of are [near] simultaneous colonizations, which sometimes happen when you expand in two [or more] directios. You can easily underestimate the resources needed for those. An addendum to the above table is to keep track of the time[s] for the next colonization[s], typically by tracking how much AM the colonizers need to regenerate, which after the first couple of colonizations is the limiting factor. (The colonizers regen .5 AM per second but lose 100 on a jump.) You don't have to worry about that in the "frontline" slots in 5v5 MP matches though; the enemy will keep you so buys you'll have a hard time remembering you had colonizers. But the good frontliners do manage to expand toward the center of the map while fighting next door.

And a BM trick: you can sell less than 100 units (or all that you have) if you use the "place on black market" as a piggy bank. Put what you have there, wait for how much you want to sell to accumulated, then sell your current lot and pull back from the piggy bank by right-clicking. Waiting for another player to buy directly from you is usually not worthwhile, despite the higher prices because waiting times can be very long (and that's because most people/AIs sell but don't buy resources.)

Well, I have a personal example that you can improve tremendously just by implementing the advanced stuff into your strategy against the AI. TBH, the only replays I ever watched, were games where I played online, I learned so much from them, understanding what your opponent did to be able to defeat you, and you don't have the feeling that is just a video as you were and are part of it.

So, my strategy to become a skilled player online was:

1. read lots of stuff online about strengths and weaknesses and figure out why some things are good or bad

2. implement what you like into your own strategy, yes, what you like, afterall the most important is to have fun, and it is easiest this way, if you do at least partly what you desire, and not just what XY player does in that replay, you are not a robot

3. test these against people, analyse losses and watch those replays, where did it go wrong, why, etc

I don't know if it is easier to just watch skilled replays and get info from them, I did not feel like doing that back in those days, I like reading long threads and comments lol

On the odd chance that someone likes playing vs. pirates (I once did), try the [small] map called Storm Front. There's little in the way of bottlenecks there (if you really want to expand) so pirate attacks are [more of] a challenge on that map, especially if the AI opponent is Aggressive Hard+ and you use the Artificial Unintelligence mod, which [among other things] makes the AI practically never lose a bidding war (by increasing its bidding frequency) in the first hour of the game, so don't even bother trying to outbid it until your econ is on par with its econ cheats.

To make your life easier on that map, play as TEC and get a Corsev (SB everywhere the pirates might strike is too expensive) and watch stupendous mass explosions; they don't completely take out the pirates, but they do soften them up. The Corsev is actually a competitive ship in MP, so it's worth practicing with it. Also, getting a trade port on every planet exposed to pirate raids is a good distraction against them because they find the trade ships really yummy, so you can also practice rapid trade network expansion on that map. (And it's a minor challenge not making your longest chain "short-circuit" on that map.)

A good benchmark if you're expanding fast enough on that map is whether you colonize the Ice on the enemy's side of the of the map before it can get to it, but you should also take the Ice and Desert [on your side] early and the middle Volcanic a little before or at about the same time as the Ice on the enemy's. The middle roids on the opposite side of the Volcanic are good practice for long distance single-colony (aka "turret") expansion. That kind of rapid multi-pronged and continued expansion is needed in 1v1 MP plays (which alas are rather rare), but it's not a good idea in the frontliner position in 5s, where you need to prioritize your fleet (after getting 2-3 roids/moons) or you'll get steamrolled. You should win in under an hour on Storm Front vs. Hard AI (military victory) with pirates on. Add about 15-20 minutes per extra AI cheat level.