I can't exactly give personalized tips for each and every player, since different people have different playstyles. But one thing: focus on your strengths and weaknesses in a fight to the death. You may or may not be good at:
Close-quarters firefights;Sniping targets at long distances;Scouting for loot and enemies;Healing and support;Grenades and rush fights; orVehicular Manslaughter Supreme.
Choose a few of these you feel good in, and try to perfect these techniques to make yourself threatening to others before refining the weaker skills. In Squad play with friends, you can arrange which people should take care of which fields: each person should handle at least two, but all slots should be filled in. Even so, practice the ones in bold: they are usually the most crucial skills the competitive player knows by nature.
Another tip is to find out which weapons you want to use. This can vary from player to player, from map to map, even from match to match. Know which guns to use and why, and learn to use some of the “hard” guns. For a more detailed look:
VECTOR: Disdained by many for its horrendous mag capacity, but shreds enemies faster than a Groza at short range. Learn to use these in place of a UMP9 in short range.UMP9: Hey, don't throw it just yet. With its extremely mild recoil and decent damage, this gun can be used at mid-long ranges on full-auto, even with a 6x attachment. It feels no more than like an AKM at point-blank with a Red Dot.M16A4: People hate it for its inability to spew fully automatic cartridges. Its insane 900m/s bullet velocity, paired up with its high fire rate and low shot recoil, can be extremely handy in sniping opponents at long range and can be equipped with up to 6x Magnification, so learning to use it will benefit your DMR training a lot.AKM: Looked down upon for its high recoil by some, but worshipped upon by others for its damage. The AK has unbearable damage compared to the 5.56mm rifles and does significantly well in short-mid range combat with a low scopeKAR98K: Don't be the idiot who doesn't know how to use a K98k. These rifles are amazing, especially at long range in the final circles. Smack a 4x or 8x and try it out.
As for weapon combinations, consider a pair that fits three ranges: Short, Medium, Long. Having a bolt-action rifle and SMG will not help you well at mid-range (60-200m)fights where a DMR could easily kill you, so prepare a good set of weapons. For a short-range firefight, any Assault Rifle or SMG will be best in the long run (you won't be needing shotguns for most of the game); for mid-range, find a 5.56mm AR (AKM and Groza are sub-par at best over long distances) or DMR, and for long-range, a DMR or Bolt-Action Sniper Rifle.
And lastly, know how to play. Have a good plan where to loot, where to run and where to hide. Instead of mindlessly rushing for kills, know when you can get them without suffering too much damage. Stay on the run instead of camping, but stay alert while you do so. And keep sound systems on! - Even with the indicators in Mobile, footsteps can be heard 60m away and ‘sensed’ only 30m away. Keep your ears and eyes sharp.
I can't give an ‘express’ solution for PUBG, and neither can any professional out there. Skill in this game takes patience and effort, and it's not easy to just improve at this game without having to feel like wanting to smash your face on a desk. But hang in there - the Chicken Dinner is for the winning stomach. Let that be yours.