Lunatic Rave is the standard BMS IIDX player now. It's also recommended to look into sims, because you have much easier ways to make them adjust to HDTV lag, and you have access to as many songs as you can accumulate. My current BMS folder has 4897 sub folders (so let's call this a conservative estimate of at least 4000 songs) which contain 143GB of data. A fair number of these are 7key only charts, much to my chargrin, but they're out there.
I would not recommend using any kind of sim or HD loader program to play the PS2 IIDX games. I've heard that the latter is acceptable to some people now, but I've read others saying that there are problems in doing so. If you're going to use a sim/emu program, I'd say you're better off to just use LR, find the BMS of Fighters sets among all the other crazy crap that's out there, and build up a massive song library to enjoy forever.
As far as getting PS2 IIDX controllers to work on PC, the two main means are using USB adapters or parallel port adapters. For the former, I personally use two Smart Joy Plus - and in general, you should pay close attention to buying any USB adapter which allows multiple controller inputs. PPJoy is a program to use for parallel adapters, but I've never had success in making it work, and Win7 complicates that setup. Alternatively, if you order a Dao or Rainbow controller now, you can request for the device to have USB ports built in and not worry about the PS2 use at all. There's also some talk that I've seen on a message board about people homebrewing a native USB add-on for the CS IIDX controllers. The main takeaway here is that if you don't have any IIDX controller purchased yet, you have options to ensure that you can make it work best through USB natively, and from there you just need to commit yourself to using arcade data (I personally have never bothered) or sims (which is the only way I've played IIDX for a few years now).
Any other tips? Practice is an important one, and the suggestion to use high speed does make following the notes much easier.
Use the Random chart modifier. It's important for you to encounter note combinations of all possible varieties, and this will keep the replayability of songs higher than without its use.
Play all songs regardless of difficulty. It will feel like you're just bashing and flailing on the keys most of the time, but the only way to make any kind of progress in this game is to play what you cannot pass as opposed to perfecting what you can pass. At least, that's the philosophy that I've always had, and I've done this because I care more about clearing 12*s than AAAing anything, and because the concept of playing one song fifty times to get an AAA is the total opposite of what I consider enjoyable.
On a closing note: it seems like everybody is a wizard at this game but me. The beginner thread on bemanistyle was full of people saying "I just began and now I'm playing Another songs on 8 stars". I think that's what's most frustrating.
As stated earlier, progress in this game comes in plateaus.
You'll beat your head against a stone wall for a week, then sit down and play the next day and magically everything will come together as if there was a physical barrier in your brain which was removed.
On the subject of bemanistyle, if anyone cares to check in, I've been posting daily entries to a blog there for a while, and I post my results of playing a IIDX sim using Extra Mode. Here's yesterday's entry:
http://www.bemanistyle.com/forum/entry.php?7462-LB-log-20130604 . If you're asking "What's Extra Mode?": the sim programs offer a way for you to play songs with all available notes thrown into the chart. When IIDX songs are made (particularly moreso now than years ago), they tend to cut every possible sound into individual files and autoplay notes as necessary, depending on the difficulty tier of the chart. In doing this, there tends to be notes which the songs have available but are never found in any official chart. Extra Mode tosses all of those extra and previously unplayed notes into the chart. I fail most songs horribly, and the resultant charts can lead to situations like Exusia having 3008 notes when it normally has 1980 (for a laugh, divide that over two minutes to see what the notes per second are), but doing this is what I do to ensure that I always have as much of an impossible challenge now as when I started playing this game more than ten years ago.