One of the very first things you should do is make sure at least one lab is being built...usually this is a military lab, but regardless you need one ASAP so you can get your first fleet upgrade...when it comes to winning the spamfest, the last thing you want to do is have a pause in production because you don't have enough fleet supply...
You also need to scout the nearby planets so you can rush the key choke points quickly and efficiently...the worst thing you can do, especially when close, is send your capital ship the wrong way and let your opponent nab an easy planet between you two...knowing what planets to take and what direction to colonize with your cap (as opposed to an unescorted colony frigate) comes with experience, but there are generally 3 things to look out for:
- Planets closest to the edge of the map will more likely give you a direct route to your enemy...especially if you don't start with a colony cap, you will probably want your cap hitting up the outer planets and your LFs going that direction...
- Controlling the inner chokepoints (those farthest from the map edge, or closer to the map center) gives you room for expansion in the long run...if you are stuck in a stalemate, this is your way out and an opportunity to gain an economic advantage...if you take the outer route and get blocked in, your opponent will gain the upper hand economically over time...
- Barrens, moons, and roids are your friends...scout intensely so you know if it is wiser to skip over planets and nab an easy grab...
You should be anticipating where your enemy will be going and using scouts to track the movement of their capital ship and initial fleet...don't wait to clear the militia at your roid and moon, start sending that cap and those LFs elsewhere once the krosov(s) are killed...2 LFs can beat an LF or an LF+flak, so push your LFs far out as quickly as possible...
A particular sticky point when going against Vasari is preventing them from building a SB in a neutral gravity well between the two of you...this is why it is important to scout and identify the chokepoints so you can send your LFs there ASAP...even if you don't want to colonize the planet, getting there before the enemy can be crucial...if they start an SB, hopefully you have the raw firepower to kill it, because if you don't, you probably will never get that planet...this is why you can't waste time shooting at militia, keep most of your LFs and your cap moving, using that fighter squadron and 2-3 LFs to deal with the krosovs and other militia...
As TEC, it is viable to go 1 civ lab and get modular architecture....this actually pays for itself fairly quickly, especially if you are the type that loves to build factories on your frontline planets...1 mil as TEC is also good, you can upgrade your LFs and get repair bays....if you are Advent, I'd suggest going 1 military so you have corvettes and you can research some techs to buff your LFs...1 civ lab as advent is useless and investing in culture that early is risky (though doable) unless you are farther away from your enemy...
What your 2nd lab is depends on the planet setup...if you think colonizing ices and volcanics is the way to go, then getting 2 civ labs (as TEC that may mean only 1 more lab)...usually though you will want military techs so you can upgrade your LFs more and get repair bays...as TEC I usually default to 1 civ and 1 mil to start, and as Advent I usually default to 2 mil...remember that you don't have to pick your 2nd lab right away, only your first...
Military techs are useful even early on, but building more ships should be your priority...until you have about 15-20 ships, it is more cost effective to add another ship than it is to research one military technology...also keep in mind that ships have "travel time" while techs don't...your fleet will immediately benefit from a tech upgrade, while newly built ships will take time to get there...so, build ships first, tech up later...
Switching to LRFs works better in stalemates when you can stockpile the LRFs one jump behind the frontline and surprise your enemy with a change in fleet composition...the problem with switching as you are pushing is that your LRFs will trickle in, giving your opponent time to counter them...also, LRFs are slower and so take much longer to reinforce the fight...remember also that if you are winning, having ships that move fast is going to be very important so that you can pursue caps or quickly get to planets to snipe constructors, emergency SBs, or backup labs/factories....in short, LFs are better while pushing/winning while LRFs are better while holding...
In general, LF+corvette fleets are better on a cost basis, while LRF+flak fleets are better on a fleet supply basis...this is why it usually is better to start with LFs and not rush LRFs ASAP, since early early game cost is more important than fleet supply efficiency...of the whole early game quad counter, Corvettes vs. LRFs is the weakest counter while flak vs. corvettes is the hardest counter, so you probably should not lead with a corvette spam as TEC or Advent...
As for starting caps, as TEC I'd go either Marza or Akkan...the Dunov actually isn't too bad if you face Advent since EMP does AoE shield damage, but the Marza has a better endgame and is useful against all 3 factions...as Advent, Prog, Halycon, or Discordia are probably the best options...if you go Prog, remember that shield regeneration is useful for countering Orky rushes as well as MB (lvl 3 shield regeneration actually counters it near perfectly), so don't pick your 2nd ability on the Prog until you see who you are fighting...if it is Vasari or TEC with a Marza, strongly consider shield regeneration over malice...if you go Halcyon, ADA is your friend, and you probably don't want to bother with TK push at such an early stage...
One final note...if you are facing Illuminator spam, do not try to counter it with corvettes...even with TEC corvettes you will barely win, and if they have malice, your corvettes will be shredded...when facing lum spam, spam your own LRFs or go for heavies...I've seen people try to do fighter spam but usually there are enough disciples still around that the aerias drop like flies...