If you want the politician to do things in parliament, be clear which session of parliament you're aiming for. Organise Your Delegation. If you can organise representatives of other groups also concerned about your issue, that's great. It shows you have wider support than just 1 person or group. Also bring someone with personal experience of the issue if you can.
Individual experience gives colour to what can otherwise be just dry facts.
Further, statistics can often be questioned, but no one can deny personal experience. Finally, try to bring a member of the politician's electorate. It makes your delegation more important to the politician and makes them more likely to act on your requests. Try not to go alone. Others can give you confidence and might be able to think of counter-arguments when you're stumped for words.