Walcott was on the scoresheet in Monday's victory over Chelsea.
He told arsenal.com: "It's just something I've worked on and hopefully it can continue because I've missed a lot of the season so far. I've got nine goals, I'm pleased with that and hopefully that can continue.
"I've been practising every day in training. It doesn't matter how old you are if you practise after training. I remember when David Beckham came to train with us, he still practised his free kicks.
"Me growing up to see that, it was great. I learnt from that. I've been practising my crossing and finishing when I can after training when they [the coaches] let me.
"I just feel that we need to concentrate on Wednesday, we can't dwell on this result. We could be disappointed if we win against Chelsea and then lose at Wigan."