I play solo exclusively, since my multiplayer mates aren’t doing this game.
Note that there are the same types and numbers of robots, whether there is one player or four players. The solo player must be very stealthy, and plan out any actions, and even plan routes and travel carefully. Resource management is crucial, as you will have 25% of what a four person team would have, so consider that before taking any actions. Avoid being surrounded out in the open–it’s very unpleasant, indeed.
I put my early skills into speed and stamina, because running away is often the best option, and some bots are very fast. You can snipe the beacons with a suppressed sniper rifle [takes several shots], and then derp out to a ‘safe house’ [some not so safe] without having to engage the protecting Runners, if you want to.
I have yet to be brought down by a Tank or Harvester, as I usually keep away from a gunfight with them, but I have destroyed them when absolutely necessary, with one exception. If have a good tactical position [church bell tower], you can bring down all enemies with just sniper rifles–including Tanks and Harvesters. I used all three sniper rifles to do that, just to see if I could. It did take awhile, and selective targeting of components, but it can be done. I did have plenty of ammo, but shot about 200 rounds.
You might be advised to wait for the patch [due this week] before starting a game, but that is your choice. The inventory system is a pathetic joke, and several missions are easily broken, or are broken already. The weapons ballistics are just silly, IMO.
The game has great potential, and I am still playing, regardless of my many frustrations, so I do like it a lot. However, it needs fixing in several crucial aspects. Good luck.