I would consider myself an expert on this topic. I have stick straight and thin lashes but I believe I've finally found something that works. There are a lot of steps, so...bear with me.
1. I first curl my lashes with a heated eyelash curler. I'm currently using the 'Diorshow Heated Eyelash Curler' ($25, at Sephora). But I also really love the 'Blinc Heated Eyelash Curler' ($25, Blinc website).
2. I go over that curl with my Shiseido Eyelash curler (the gun metal color, it's a newer version). This particular curler works so much better for me than Shu Uemura's, but it really depends on your eye/lid shape.
3. Use a WATERPROOF mascara. Covergirl's Lashblast waterproof is probably my favorite mascara I've ever used (including high end, low end, etc). It holds my curl forever, no smudging, but it gets a little messy. I also like the Maybelline One-By-One, but it doesn't hold my curl/thicken as well as Covergirl.
I'll be honest, it takes a while. But my lashes stay perfect all day, and I think it's worth it. And yes, I do this every single day. Haha #beautyjunkieproblems