A common way of getting experience is to join a local club and go diving. Of course this depends on where 'home' is, but the only way to get experience is to get under water and go diving. Even diving in pools, lakes, quarries and the like will mean you get to sort out your core skills: buoyancy, finning and trim. Not to mention practising all the skills from your course.
Most clubs will welcome you with open arms. You will need to do some research on the best clubs to join; this can be on the basis of how much you "like" the club and spend a night or two with them to get a feel for the people and the facilities available.
If you live in colder climes, then find a club with regular pool nights. Whilst it's nice to sit around in a bar talking about diving and drinking beer/whatever, it's not gaining experience! You need a wide variety of people in a club with a range of experience; from recreational to technical. You need some instructors in the mix too.
Be aware of the Local Dive Shop (LDS) who are after selling you lots of courses. Whilst courses are an essential part of diving, you must have plenty of time to practice and assimilate these skills before you go on to the next level.
Same goes for buying kit. We all love looking at diving bling, but be careful of what you buy as you don't know what's good and what's bad (I've very little of my initial purchases left as virtually all of it was wrong for my current diving -- most of the kit was unsuitable!). The LDS is an essential part of diving but they are most definitely not all created equal -- their primary purpose is to sell stuff even if it's not right for you (i3 BCD anyone?)
Again; get diving. Find buddies either in a club or online. There's lots of different dive forums to use. Oh, and beware of the internet "divers" who frequent some of those forums, especially the ones who don't! Whilst there's a lot of helpful info out there, there's also a lot of not so good advice.
As for commercial dive trips, as long as you're honest and up front with them for your experience -- even if very limited -- they will be able to buddy you up with someone suitable. You will need your certification card, PADI's a good enough agency to get started with. Cannot stress how useful it is to find your own friends or shop/club to go diving with for practising.