Well
You are gonna have to decide on what sequencer you would like to work on. And there are quite a few to choose from!
Here's my little rundown on the ones I have used:
Cubase
My own main DAW workstation platform. Have used this since 5.1 vst, and have learned pretty much all the features I need. Can be very intimidating to start out on, as it is really rather complicated beyond that first glance. Excellent MIDI support. Pretty good Audio platform as well. Awesome dualcore support if you have that, so it runs really good under heavy load.
Logic
Now Mac only (you didnt specify platform), and oh how I miss it.
Has pretty much all the same features as cubase, but with logic you could set up your own sessions with alot more customisability, wich is what I miss the most. Also it can draw automation right on parts, wich is something I miss in Cubase as well. Also extremely daunting to start out on (as in, may take a few hours before you even get a sound out of it)
Have not used it since it became Mac only however, so someone else would need to fill in my blanks.
ProTools
This is what all the pro's use, or so they say. The best audio platform for recording, bar none. Extremely fast and good workflow. MIDI platform is a bit icky however. (this might have changed since I used it the last time)
It is the industry standard recording software, so theres constant updates, and digitech release excellent hardware interfaces for it. Probably not something you will want to use for electronic music.
Digital Performer
Also mac only. Have not used this very much at all, only observed others use it. Seems to have most of the features of Cubase and Logic. So if you are on a mac, it is certainly a decent option.
Ableton Live
Now this is a different beast!
I use this often for practicing on my bass, as it allows me to warp songs to my own tempo and play along to the original pitch with ease. It can do so much more however!
Some may say that its "loop based" and they may be right, but there is a full sequencer as well, wich allows you to arrange pretty much like any sequencer out there. A little short on features on this end however. Out of all the DAW's i have used, this is the one where I find myself working fastest and most effortlessly. Very intuitive interface, and very very fun to work with. It is also extensively used by DJ's in live performances. Many will say that it is meant only for live performances of songs, but I say its fully capable of writing new material on. In fact, it excells at doing this quickly and easily. I like to think of it as a music notepad of sorts.
FL Studio (Fruityloops)
The bastard child of the audio software industry!
Has so many strongpoints, and you really cant go very wrong with it. Has been developed alot since its release. Evolving from a simple fun loop sequencer into a full fledge production platform featuring audio support, good mixer and some of the most weird and bisarre effects and instruments ever created.
Also if you purchase it, you get free updates for as long as you walk this earth, something that is a big bonus to be sure.
Another thing, people I know that use FL usually send me some of the most creative and "out there" tracks I have ever heard. It seems to appeal for those really experimental tracks.
Reason
A closed enviroment that doesnt let you use any outside instruments like VST or AU. What you get is what you have. Because of this many people refer to it as just one instrument.
It can be much more if you know how to use it however.
Comes with a vast arsenal of sounds, beats and effects. So this is the one you want if you want to start churning out mad beats from the get go without hunting for samples, synths and sounds.
Many people find the sequencer in Reason lacking, and I am one of them. You can however use something called ReWire and route the sounds from reason into other platforms. Ableton Live and Reason or Cubase and Reason are very powerfull combo's.
Buzz
The natural evolution of the mod trackers of old.
Its free, powerfull and very very strange. Some very well known producers swear to it however. (James Holden, is one)
You will never run out of strange instruments to use.
EnergyXT
Not for the faint hearted. It is a fully modular designed sequencer, where you basically build and choose your own components for your platform. Full support for VST and audio, as most of the others. It is being continually developed by a great team of dedicated coders and users. Post on their forums about a feature, and you might just see it in the next release.
Also, compared to alot of these, it is VERY cheap!
If you loved technics lego as a child, you will probably love this.
Tracktion (2)
Mackies own sequencer. Some people like it, I dont.
It does have a few cool features, such as the ability to drop effects on individual parts on the arrangement view. It also looks really shiny and fresh.
ReBirth
I just had to add this one, since it was the first program I started to use. It is basically 3 emulated classic instruments from Roland; the TB-303 (of these), a TR-808 and a TR-909 with some effects added. Arrangement is done via a classic hardware like pattern sequencer.
It was made by propellerheads, so it is basically the predecessor to Reason.
If you were into acid house you will absolutely love this. REACH FOR THE LASERS!
Okay, thats all the ones I remember off hand as of right now. Im pretty sure I have covered all the major players.
Now, If you like FL as you said you are using right now, I will suggest you use it untill you get the hang of production a little better. It has everything you need right there, and there is a great community around it with alot of people dedicated to teaching others about the ins and outs of it.
The big ones like Logic, protools and cubase will set you back a considerable amount of money, and there is a good chance you might not be happy with it once you get it.
If you feel you dont have a good grasp on production as it is, and still find FL confusing, I would suggest either Reason or Live.
They are alittle easier to get into. Reason especially so, since it is built from the ground up to resemble hardware instruments and racks. (you literally user your mouse to connect cords between instruments and mixers)
It is comparable to WYSIWYG html editing software I guess.
Now, first things first: Dont let anyone, ever, tell you that any of these are better or worse than the others. It is simply a matter of taste and of what you really need. You can make great music with any of these, and thats a fact.
You will need a relatively powerfull computer to run any of these (with the exception of Rebirth), as modern virtual instruments and effects consume quite alot of CPU and RAM.
A soundcard and a MIDI keyboard would also help you alot along the way.
I can reccomend the M-Audio Audiophile 2496 as a entry level professional production soundcard. Cheap and good enough to start with.
For midi keyboard I personally use an Edirol PCR-50 4 octave keyboard with 8 knobs and 8 Faders to control all those synth parameters and such. But there are many many more to choose from. Ask around.
You will want to build yourself a sample library. Now you can buy sample cd's anywhere and you can also find heaps of samples free online. Drum samples in particular, you will never get enough of those. (I have 2GB of hihat hits alone

)
Synthesizers. Samplers. Again, so many, of varying quality and field of use. If you opt for Reason you wont need this, as there are 2 samplers and 2 synths built in, along with a loop player and a dedicated drum sampler.
But for most of the others you will need VSTi's (Virtual Studio Technology Instrument) or for the mac AU's (Audio Unit? dont remember)
These can be found in abundance free online, or purchased for heaps and heaps of hard earned cash!
I offer you this website wich I consider to be the spiritual home online for virtual instruments:
http://www.kvraudio.com/
The forums will have loads of people and guides and whatever you need to get started. Many of the major developers for instruments also have their own forums there.
Some short advice on instruments: Learn the ones you have in and out. Learn how to build patches of your own. What is an Oscillator? What is a filter? What is an ADSR envelope?
If you do this, you will avoid falling into the trap of just hoarding tons of instruments just to use the presets that come with them. Become a master of your synthesizer, and then create all the sounds you have in your head with this knowledge. Trust me, you will not regret this. On the KVR forums you will find a book called How To make a Noise, wich is a free E-book that will learn you the basics of synthesis sound design.
http://www.kvraudio.com/forum/viewtopic.php?t=76293
In closing, be aware that getting into all of this is gonna take alot of effort and dedication. Getting into production and sound design can be just as demanding and time consuming, (if not more so) than learning an instrument.
Hope this helps
Have fun, and good luck.