There are several strategies when it comes to how to play Starfield. I listed the four main ways that I considered playing and then explain why I picked the strategy I did.
Just know that there is no right or wrong way to play Starfield, just whether or not you have fun playing.
I am a software engineer, so my idea of fun is setting goals and then reaching them. Some of the complaints I have seen from other people did not really apply to me. So what works for me might not apply to you, but hopefully I give enough information to someone just starting out so you can make informed decisions on what strategy they want to take.
There are four approaches you can take to playing Starfield.
1. Your first playthrough is your main playthrough and you do everything, once you get to the Unity, come back and just keep playing in your main game and ignore doing NG+
2. Your first playthrough is your main playthrough and you do everything, once you get to the Unity, you go forward and do as many NG+ iterations as you want until you get tired of it and then make your last iteration another main playthrough focusing on whatever makes you happy
3. Focus on the main quest on the first playthrough so you can unlock NG+, then speed run NG+ 10 times before doing your main playthrough
4. Focus on the main quest on your first playthrough so you can unlock NG+, but instead of speed running each NG+ iteration, you pick a new faction to do, enjoying each iteration until you are ready to settle down and make whichever iteration you are on your main playthrough and focus on whatever makes you happy.
NOTE: NG+ stands for New Game Plus and it happens when you reach the Unity in the main quest and step through to go to a new universe. You lose all your material items but keep all your mental items (like level, research, skills, and powers).
Things to consider
Things to consider, when you reach the Unity, it will display a record of your life in that universe. If seeing very few memories makes you sad, one of the first two options might be best for you.
When you go to a new universe, you leave all physical items behind, meaning all your credits, equipment, and ships. You only take what is in your head, which is your level, powers, research, and skills. If losing everything you worked for makes you sad, doing one of the last two options might be best for you.
I ended up doing the fourth option and have not regretted it. Then again, I am an engineer and very goal orientated, so what makes me happy might not be the same as you.
Here is why I selected the fourth option as my strategy:
1. Since you give up all your material items when going to a new universe, I wanted to wait until my last playthrough to be my main playthrough.
2. Since each new universe is a restart, I wanted to do each of the factions as a separate playthrough. That way I can decide which ones I want to do again in my final playthrough.
3. Since I wanted to focus on building outpost, I used some of the playthroughs to not only to gain the skills I needed, but also get some practice in building outpost so I have a better idea what I want to do on my final playthrough.
4. I wanted to best starborn ship and armor for my final playthrough, so my target playthrough is NG+10. I also wanted to have my powers maxed out.
NOTE: If you visit all the temples found when you reach the Unity, you will have only unlocked about half of the powers for that playthrough. If you want to maximize upgrading all your powers, I highly recommend going back after visiting the Unity. When you do, you can find most if not all the other temples. Once you run out of temples, then go back to the Unity to go to the next universe.
On your very first playthrough, you can talk with the Hunter (a starborn character you will meet near the end of the main quest) at the Viewport bar in New Atlantis when you first arrive.