If you're just starting ... pick some low-cost plants on learn-on-the-fly ...
IMO that's the easiest way. Don't go spend $$$ on a
CO2 system or expensive lights ... get some cheap plants (as others have listed above as low-light plants) and just give it a try. Then maybe try adding some plant fertilizers (as most are all that expensive either).
That's just my opinion as a novice plant grower. If you want to go whole hog, then go buy some high wattage lights, some nice substrate, get the
CO2, etc. But I don't think you'll find all those things necessary when starting out.
There's a good possibility that you'll find some plants that will do well for you without all the extras.
I started with 30w of light in my 55g with no
CO2 or additives and have my java fern growing fine. The jungle val didn't do very well, the java fern was fine. Then i decided that I like plants and went out and got a C-USA 130w Satellite unit. Now I'm pushing 3
wpg, but I don't do anything more than have pool sand in my tank and add some planttabbs every week or so. I'm not saying that fertilizers and
CO2 aren't worth it, cuz I'm sure they are ... but I haven't had the $$$ to invest in all that and my plants are growing and happy (java fern, jungle + itailian val, ludwigia, cabomba, amazon sword & myrio)