I am looking at creating a tech-priest for an upcoming game I am in. I know there is the Mechanius Secutor advanced class, and will probably take that at the correct time. Other than that, anyone have any suggestions or ideas on what I should look at and/or take?

The Divine Light of Sollex Background Package (from IH) is maybe worth taking a look at, if you want to "design" a martially minded Tech-Priest. Besides, if I remember correctly N0_1 made some alternative career path (i.e. Skitarii) for the Guardsman somewhere here on the forum.

Secutor is the way to go if you want to become a walking tank.

But dont forget to keep up your tech skills, as this is where other chars will not be shining and having a 3th great fighter is not of so much use if you need to get that lift to work again....

I like to take the Craft Armorer skill listed in the errata. Playing a Secutor means you are more militant and you will probably end up with a lot more strength than normal from the array and other cybernetics. Craft armorer goes off of Str instead of the normal Int, which is much easier to raise with equipment. The Mining Healot Augments (inquistor handbook page 139) are also useful if you dont mind tanking your Agi score.

Following the Strength theme, if you go Void born for world, take the Battlefleet Calixis Varient if you are able (Inquisitor hanbook again). It will eliminate the strenght loss from void born and grant an extra weapon talent to help with secutor entry.

Mono-task cyber skulls are also very impressive out of combat. Pick up a pair for tech use or trade armorer to help you build. You can have two additional people help you on a task, each one lowers the diffuculty threshold by 1 degree.

For a stranger career path, the Daemon hunter book has the Ordo Sicarius Initiate advanced career path. Any class can enter and has psy-rating 1 as a talent advancement. Only way for a tech-priest to get a psy-rating that I know of without an elite advancement. Now psy-1 does not sound all that impressive until you are out of combat. The power Luckly has a threshold of 6, so you only need to roll a 3-10 if you have a willpower of 3. It lets you re-roll any roll by the end of your next turn. Free fate point for out of combat rolling, just don't start crafting until you make your threshold roll. Likewise Knack at a threshold of 7 gives you a +10 to any non-combat roll. Depending on your interruptation, I would think you could fire up Lucky round 1, knack round 2, and start your crafting roll round 2 with the remaining partial action. If that works you can pick up +10 to your craft roll and re-roll a failure.

Imperial world is also a solid starting choice. Nothing really glaring for weaknesses outside of the smallish hit to Forbidden Knowledge checks as well as getting a mess of common lores as basic skills that you may or may not actually take as actively trained skills (outside of literacy, you've got that by default). The big draw over the Battlefleet Calixis Void Born is the fact that you get two more wounds on average for not as large a hit to fate points as the trade-off might entail.

My two thrones have always been that the Skitarii grunts have just been Guardsmen with augmentations who worship the Omnissiah while only the officers (or some specialists, like the Electro Priests) are actual tech priests.

Well, there is the Skitarii rank of Tribune which covers all the NCO/CO ranks below High Command (which is Magos and above). The tech-priests are usually given deference regardless of rank (unless said Skitarii orders are from higher up) and usually act as support for the main Skitarii forces rather than leading them (they usually delegate that to the Tribunes).

You also have to remember that the non-Tribune skitarii aren't exactly known for flexibility and initiative when there aren't any marching orders. The augmentics in Skitarii tend towards cranial modifications that prize quick compliance and regularity at the expense of intuition and independent threat assessment.

This is where are Myrmidon differs though, they actively study war with the fervor a tech-priest would have towards technology and science. Main advantages a Myrmidon tend to exhibit over Skitarii is a broader range of weaponry skills, more capable of independent action in combat, and can be almost as heavily armed/augmented as a praetorian servitor. Myrmidons fill roughly the same kind of position in the Skitarii as stormtroopers do in the Imperial Guard.