I recommend all beginners start with Touhou 7: Perfect Cherry Blossom as their first game. It's a relatively easy game for Touhou standards, with the main gimmick being a respawning shield that allows you to absorb a hit or be detonated like a bomb to clear the screen. Character hitboxes are also pretty small in this title, with Reimu's being the smallest in the entire series. Touhou 8: Imperishable Night is also a great place to start, as it has even easier patterns than PCB and hands out bombs like candy. The time mechanic is somewhat convoluted, though, so I'd recommend reading up on how to collect time orbs before playing.
I'll also recommend
thprac, which is the practice tool most the community uses. It lets you skip to specific stages sections or spell cards at your will, letting you practice tricky sections to your heart's content. Word of the wise, though, using it for EoSD requires a
locale emulator to run the game in Japanese, so do keep that in mind.
Once you start getting good at the games, I'd wholeheartedly suggest Touhou 11: Subterranean Animism as the best game in the series to try out. Fair warning, though, it's a
very difficult entry, even by Touhou standards. Once you master it, though, it becomes a blast and a half to play.