Paths to victory vary much when you play against live players vs when you play against only AI.
Playing against a mix of live and AI players should be treated the same as just playing against live players. Live players can not only be much more cunning, less predictable, but also prone to mistakes. It would be wise of you to at least diplomatically deal with the remaining live players in such a way, that you can effectively conquer and hold on to the AI stars.
If the beginner game gets down to just yourself and just 1 other live player, then propose a racing agreement to not attack each other until all of the AI are vanquished. Placing 2nd in the beginning game of NP2 is a good place to start. Placing 1st is more of an ego stroke that some of us have achieved.
The long way to a solo win vs all remaining AI can work in about 15-20 production cycles (~500 ticks away)…
Playing vs many AI, you will need the Econ to keep enough purchasing power for future Sci purchases…
You have a lead in stars, so this should allow you certain advantages for building. Lets hope your star count lead is 40% or more vs your current AI player target. Star count is not very accurate to predict a game winner at either the early or middle stages of any NP galaxy. It does count towards the end. Comparative infrastructure counts of Econ, Ind, Sci, tech levels, ships and carriers give you a much better picture of the strength and sustainability of maintaining or growing an empire’s star count.
Research Exp exclusively for several levels (10 production cycles worth at least). Exp tech is the mother of all other techs in this game. I would keep it up until I reach about double the Weapons (or whatever the highest next) tech level. Do not worry about falling behind other AI’s. Since you have a lead in stars, your eventual Exp lead will pay off about 240 ticks or 10 production cycles away. The Exp bonus from each production cycle will get progressively better.
Ignore bonuses to Range, Scan, Mfg, and Weapons, but strategically follow up on Terraform and banking technology bonuses. Then keep pursuing Exp.
Build more Sci. Build more Econ too. Limit your spending on Carriers, Ind, and warp gates. Build a few Ind only when it costs much less than the Econ. I would say reserve funds to build Econ until the cheapest one is 30 credits more than the cheapest Ind. Keep building Sci until the cheapest one is over 250 credits more than the cheapest Ind.
Never trade out Exp, Weapons, or Manufacturing to the enemy players.
No need to bribe the AI players anymore. That just slows you down.
Figure out the nearest (hopefully smallest) AI neighbor that you can concentrate your attacks upon. Do not attack any of the other AI players until you KO this particular AI player. Concentrate your attack 1 AI star at a time. Use the battle calculator to make sure your attack has enough to overcome AI counterattacks from at least 4 neighboring stars of the same empire. This step requires much patience.
4 b Keep adequate ship counts on or near the borders of all the other AI players who may attack you. An outer perimeter of ship concentrations should be OK. The AI may launch deep attacks to your interior as the AI gains a lead in Scanning and Hyperspace range tech. While you are awake, it is easy to buy a carrier with the right amount of ships from one of the outer perimeter stars to reach an interior target for defense against any upcoming AI attack.
Continue and slog through with steps 1, 2, and 3 cycle by cycle until you take down that 1st AI down to the last 1 or 2 stars. It is wise to wait for the AI to send a carrier with many ships away from a nearby high resource star so you may attack it before claiming lower resource stars.
(5.) After you KO the first AI player, pick your next AI player target. This is where the momentum helps you. You will soon find out that the 2nd KO is easier than the first. In the midst of the 2nd AI conquest, your EXP tech lead should be sufficient enough for you to switch research towards Mfg, Weapons and the other key techs. After the 2nd KO , just research Mfg and Weapons, You no longer need to buy Sci at this point. Shift that part of your budget towards Industry. Victory will be yours either during, or soon after you KO AI player #3.