Many of us SEO types are not college educated programmers so this can lead to technical SEO aspects being overlooked or not given the priority it deserves. As more users move to mobile devices, it has become even more important to get the technical aspects right because it can help Google rankings and more importantly will help conversion rates.
1) Monitor everything - You should be monitoring your websites to make sure they are loading up quickly. Slowly loading pages upset users and it doesn't make Google happy.
2) Update everything - Security is very important and you are probably not taking it seriously enough. That will change after a hacker takes control of your website because you didn't update your old wordpress version that has more holes than swiss cheese.
3) Regularly test your redirects - You want to make sure your redirects are working. More importantly to me, you don't want multiple redirect strings because that may damage the link value being passed through the string.
What technical SEO advice would you give to newbies or veterans who are too embarrassed to admit they don't know everything?