I find it helps when you can make things visual, tactile--multi-sensory.  Create a routine whereby the student follows a process for sounding out words--stretching them out (with a swoop of the hand), finger-spelling (putting the sounds on their fingers), then write each letter for each finger as they say each sound, then touch each letter and say the sound, slowly blend, say it fast.  (Using magnetic letters to build the word is another step that can be added before writing or used in place of actually writing the word.)  

Keep the process consistent and have the student use it consistently.  They will "graduate" through the steps and eventually not need them all.  I find it supports confidence.

This is the method that the Barton Reading and Spelling program uses.  I find it helps students keep sounds in order and even helps them catch errors in their work.  

Hello!

We are seeing some of the same issues with our students. They can often decode words but have a lot of difficulty with encoding. We have been incorporating the Orton-Gillingham approach with our PRESS lessons. The students will pound and tap words using their hands/fingers. We then have the students write words/sentences using the same skill.