Technically-speaking, there could be a problem, which SLR do you have? Be wary that the cheaper ends of the scale (at least, what was the cheapest ends when they were new), the viewfinder will show less than you get on film, some as low as 80%. Not a problem per se, you get more on film than you framed, but it means you have to crop in the darkroom. The better ones (when new) will have bigger viewfinders, my EOS 3 (once the second-best they everr made) has something like 97-99% visible, the 1/1n/1V I think all have 100% viewfinders.
Ditto that with Rangefinders, some brands set the frame lines to be correct at infinity, some at 10'/3m, some deliberately crop tighter so you get more on the film than what you think when you click the shutter (at least it's better than getting less).
There could also be a problem with shutter-lag, the time from when you press to the time the photo gets exposed. Again, the more expensive the SLR, the better (as a general rule). Canon's latest flagship digital which shall remain unnamed, it takes 55ms, down to 36ms with some special functions. EOS 3 also has 55ms according to an unquoted guy on a forum i just googled. Cheaper SLRs are probably slower. Some leaf-shutter rangefinders are probably faster. My MF SLRs are damn slow, I saw a smiling person when i clicked the shutter, when I developed the film I got a stupid expression with half-closed eyes. Digital P&Ss that autofocus each time can take 3 seconds sometimes (hence I don't use them).
Also, there may just be a metaphysical problem, in that you said you were a painter. Maybe you're still looking through "painter's eyes", you're seeing the world how you want to paint it, not how it will appear on film. You need to learn how to see through photographer's eyes. And the best advice I can give on that is practise practise and practise.