The best tip with tackling is to go low, try and wrap your arms around their shins/ankles and you should bring them down, if you go for the thighs or body and you're small they'll likely run right through you. Also if they've gone past you try a tap tackle as it could still make them trip up. When attacking try to avoid runing into contact as you could get the ball stripped from you, instead try and go outside the defender keeping the ball in the arm away from them and using the closer arm to hand them off, or you could committ them to the tackle and pass just before they hit, this will create some space for a teammate and may help them like you more. Also do sidesteps/zigzag your run to make you a harder target. Hope this helps and good luck
Sorry, there are no 'sneaky' tips to make a tackle, you just have to go 100% every time. Do that