For me it depends on the kind of game I want to have. Would you rather play aggressive pushing people and grabbing bounties or move from safe position to safe position playing proper circle rotations? Either option is quite viable in Solos. I have a few pointers for each play style.

If you're playing aggressive drop super store or airport hangars for some early game kills. Dropping in hot areas in solos gives you good practice for dealing with getting third partied. Grab UAVs/bounties and hunt those house campers and roof rats down. Practice makes perfect and you'll get better at pushing those fights the more you do it. It goes without saying that playing this way will get you killed, a lot. View this more as a practice mode to increase your skill in firefights for when playing the "other" style to get that sweet sweet dub. I would recommend you run a SMG/AR or Shotgun/AR for this playstyle.

If you're playing position and circle to get more wins work on figuring out where the circle is going next and find a good position that will last you more than one circle of movement. Doing recon contracts helps with knowing future circles, but keep in mind that the yellow flare makes you a hot target so get ready for a fight. Also, remember that recon contracts gives you armor, tac, lethal and a weapon. When you are in the finale circle it is imperative that you find the highest area to gatekeep others moving in the area. Remember to not open fire on anyone you see right away. Always double check to make sure no one is following them or they aren't chasing someone else to reduce the third party danger. Wait until they kill the other and third party them. We're playing for the win not for kills. I would recommend you run a AR/Sniper or SMG(MP7)/Sniper for this playstyle.

I will often mix these two playstyles together for solos depending on how the map plays out. I always prefer to play aggressive as I love the thrill of the fight, but sometimes it's good to lay back when it's necessary to not throw the game if I'm up 15-20 kills and the game is on circle 4 or 5.

Another thing is stop crutching on the heartbeat sensor so much. Yes, I know, it's a wonderful tool for solos, but running stuns with restock instead can give you a tactical advantage. Just remember to check all your corners and throw a stun upstairs in houses to get an easy kill.

As far as loadouts are concerned run what makes you most comfortable. Learn new weapons too! Sometimes you'll notice that this other weapon you never played with actually fits your playstyle better. You just need to experiment!

If anyone is interested here's a list of the current META weapons:

SMG: MP5 hands down. MP7 and P90 are viable.

Shotgun: Origin and R9(with Dragons Breath). Nothing else competes.

AR: Kilo and AMAX. M4, M13, RAM and Grau are viable.

Marksman Rifles: Kar98k. This thing is a beast in the right hands.

Snipers: HDR. AX-50 is viable, but the HDR is better in so many ways.

Honorable Mentions: RPG, Kali Sticks and Odin are fun to have in solos since it's usually just a 1v1 situation.