The strategy should be shut up (I mean, use shift to move ) and hear the enemy's footsteps, and if you are sure of the enemy's position, shot him from far away (Warning, if you fail, the enemy can see/hear your shoots)

Use shift for stealth walk and then take the enemy player out with silenced M4A1 or USP. It will be unfair to the enemy, I am 120% sure.

Strategic tactics are also useful like, you say to your teammate go take the other way and do a ambush on the opposing team and then you plan it accurately enough to take out their team and win the round. Some clans are good at this.

Firstly, control of everywhere.
If you playing it 1vs1; you need to shoot some places, maybe theres no enemy but if you shot there, u can see there is enemy or not.
Camping
When you get low hp you will camp.
Best camping area for ct= not spawn area, bomb plant B
for t's=tunnel or up of map.
Weapons
In my opinion;dont use awp or heavy weapons on 1vs1
if you miss with awp, you will die %99
If you use m249, u will misshim cuz of big map.
Aiming
If you see enemy; it is rushing=aim front of enemy it will works always.
If you 2 camping;... idk, you cant fight
Go rush if you have more hp than enemy.
Note:Take a breath and shot him. You will see his dead body.

Don't use shift for walking. its hard to use.
Change it to SPACE button; its very easy for stealth.

You obviously need:

Good Internet connection
Low Latency
Good mouse control
Weapon Script
Good reaction
Decent tactics

Some newbie to the game, said something like "Always keep the cursor on the opponents head". Do not listen, that only works in bot games, and really low latency.

Anyway, there's a few good Youtube videos on CS2D frags, maybe you should check some out.

if you dont know where your enemy is.
i suggest u dont walk coz if u do the enemy could shoot u easily if they know where you are.

For you, but for us Relative movement are easy because you only need to master it for a few days.

No no, it works on 3D games. Do you think someone can do a headshot in CS2D?

I was training more than 100 days... So i am a PRO (Pros are the professional players. More kills, less deaths, like me...)

Well, @Zupaman, It is hard to know, who is a PRO, just because pros are often "noobs hackers". Also, all can say "I am PRO", but words aren't enough.
But of course the best training is just playing, if you play enough you can be good.