Here is a list with some of the games that I played, I will try avoid already mentioned ones.
Season of Sakura
Three sisters story
Dividead (clasic)
Nocturnal Illusion (personal favorites and they are my starting games)
Maid's story
Chain the lost footsteps
Adam the double factor
Eve Burst error (adam and eve are from the same series, both are great)
Desire (great game)
Kotobuki (really fun)
Sensei 2(good game, even thought I am not a great fan of rape games)
Ever 17 (a must play, great game and a personal favorite)
Pretty soldier war (good game, the battle system and the h is kind of poor, the story is good)
Piece of wonder (good game, no h, but a great story)
Yin-yang xchange alternative (haven't played yet, but I just posted a torrent of it and am seeding it right now)
Love potion (good game, one of my firsts too)
Fatal attraction (good and one of my starters too)
Princess maker 3 (it is a nice game, but don't expect much of it since is kind of hard too)
Sentimental shooting (really fun to play and relax, no thinking needed, just fire and kill the clothes from the girls)
True love (a classic, a good game, one of my first games, a must play to any fan of dating sims)
Paradise heights 1 and 2 (they are good for the h, with a reasonable plot, they are a bit old but good, also on my list of first games ever played)
Critical point (really good, with a good plot, tons of endings, you can end on a bad ending quite easily too)
Tokimeki check in (really good too, with a good plot, a nice game to relax and enjoy the story)
Gibo stepmother's sin
Tsuki possession (it is good, but is one of the rape games, if you don't like rape, then this is one to avoid)
Slave pageant
Idols galore
Fate stay night (good game, and I am seeding it now, so you can download it right now if you check my posts)
Well I guess that this is a good list to start, check on the suggestions of the others too. You might find some torrents for the games on the net, same for walkthroughs. Just get ready as many GBs, CDs and DVDs you can get in your computer some of those games are large while others can be burned on a CD or two, others will require at least one DVD.
P.S. they are DVD game but they are good too Phantom of Inferno and Natsuhiro no Sunadokei (houglass of summer). Be ready for several hours of play with any of those two.