There are not really any places to get discounted DLRP tickets over here. We usually buy them from the Disney store before we leave, just to avoid the queues at the ticket booths at the park entrance. However, unless you go at high season or weekends the queues are not bad at all.
Try to avoid weekends and you will have a much less crowded park, although midweek opening hours are shorter.
We often go for single day trips en route to somewhere else. We have one planned for July. Our tactic is to go first to the Disney Studios as most people head into the main park first. We do the main rides in the Studios, such as Aerosmith and Armageddon and then head over to the main park around early afternoon.
I don't know where you are planning to stay at the park, but if your budget can stretch to it you should try to stay in a suite at the Disneyland Hotel. It's a bit pricey, but you also get a VIP fastpass. This is basically a fastpass that is valid for the entire length of your stay at the hotel (one night stay is a two day fastpass). This means that you can just keep on going into the fastpass line on every fastpass ride in both parks. It is the greatest thing ever and means that you spend very little time standing in queues.
If you want any more DLRP tips then just post in this forum. It's where I hang out. BTW, I'm not sure of your dates of travel, but the Whitsun holiday weekend is very busy, so best avoided.
