Which basic football skills have the greatest payback in the shortest amount of time?
Let me offer my advice about what you can improve quickly in addition to the existing answers and working on fitness and ball control:
Positioning
You already watch football. Start watching the players' positions in various scenarios, especially the right-back in your case.
You give yourself a much better chance at everything in the game if your positioning is correct. Some things to consider as a newbie right-back:
- Move up and down the pitch in line with the other defensive back line players. This means that you are working together to catch attackers offside. If you are sitting deeper than your teammates, you risk it being you that plays an attacker onside.
- Show the attacker down the outside. The safest option as a right-back is to force the winger down the outside of the pitch. Shape your body so that it almost looks like you are inviting the player to run past you on that side. Ostensibly you are! Trickier players love to come inside and have the fullbacks twisting and turning. Keeping yourself between the player and the goal vastly improves your chance of tackling.
- When defending corners always make sure that you are closer to the goal than the player that you are marking. It seems like common sense but you'll be surprised by the number of players who don't do it!
Communication
You've been talking most of your life so don't stop it on the football pitch. Advise your teammates of attackers that are posing a risk, tell the right winger when you need cover. Hopefully you've also got a goalkeeper who talks a lot. In that case... LISTEN! As a defender it's great having someone who is keeping the defence well organized.
Play the easy game
You're not David Beckham. So don't try 45-yard diagonal passes across the pitch! Look for the short 5-10 yard passes. Play the way you are facing and give it back to the teammate who gave you it if you want to. You're more likely to complete these short passes and your confidence on the ball will increase with the success that you have. Also, don't be afraid to turn around and pass backwards or sideways. It's better to do that and keep possession than to try a difficult forward ball and gift it to the opposition.
"If in doubt, hoof it out!"
Your primary job as a defender is to prevent goals. If this means that you need to kick it a mile off the pitch to foil an attack then do it. If you're under pressure it's better to kick it out for a throw-in rather than make a mistake that adds to the attacking danger.
I'd start with the above. Working on stamina and ball-control is very important but, if you're looking for quick-wins, go for the advice above for now.