1st step: If you can't afford a gaming computer, buy a gaming mouse there around 40-70 dollars. I have a logitech but it's close to a gaming mouse. Heres a link to see some gaming mouses http://www.alienware.com/ 
2nd Step: Watch Pro PvPers, I tend to watch BajanCanadian and StimpyPvP to see there pvp skills. I've learned much like doing a swerve or turning off particles to get more Fps and less lag.
3rd Step: Click fast, No I don't mean like "DUHUHH You have to click fast" Just click fast go on your mouse settings and change your clicking speed. 
4th Step: Watch your durabilty, One way to get see your durabilty is to use mini-maps and seeing on the left/right/bottom/top it will show how badly damaged your armor is or some servers come with that plugin.
5th Step: Craft/Enchant weopan First then armor. The reason why you need to craft/enchant a weopan If a player with full diamond with no weopan just a fist was fighting you that had just a Diamond sword no armor you are probably gonna win if  you have good pvp skills.
6th step: Do not Back-Stab. Backstabbing is for the newbie you need to be legit and face them face to face. You could do a hit in the front and then turn around and start back-stabbing so they now someone is fighting them but other than that no BACKSTABBING!
7th step: Have potions/Goldenapples/food. Potions are the best way to win in a pvp fight you can throw an instant damage and poision at the enemy and you could just run and they would run after you and then you turn around and BOOOM 1 hit there dead because of the poision. but you can splash potions for yourself like Regenration, Strength, Instant-Health for yourself. You need to have food all the time so you can regen faster than having no food and you don't want to be slow and fighting. Golden apples are the best! Depending on what type they are, It can give you absorpotion,Regen,Fire res, Resitance,

8th step: Don't unleash your rage. This is what I say to players, I never do rage because I'm a calm person. I tell them just act cool and Say "Good Game" and they would say the same thing instead of you insulting them and they insulting you and going on and on forever.

9th step: Don't hack, Hacking is for players that are bad at pvp and Hack-to-win. And once they get all the stuff they need there wouldn't be no reason for hacking.
Well There might be a part 2 
to this and I hope I improved some of your guys PvP skills
Fact: PvP stands for Player vs Player
Well Thanks for reading and have a nice day!
-Manliy 
Edit: Make Part 2 Today so watch out for it and also check out my projects I've built