Lol time for Roman tactics.
Line Infantry, as in Hastati, Princepes(reforms or not for those 2), Socii Cohortes/Hastati,
or Phalangites(occasionally) are grouped into one large line, and other troop's positions
are based on this line. (L-I on graph.) 6-12 units of this type.
Socii Hoplites and Triarii(reformed or not) go on either flank, usually in groups of two. (F-H and F-T
on graph.) 2-4 units of this type, usually.
Ranged troops(Velites, accensi, archers, leves) go in front of the huge-ass line. (S on graph.)
I usually have around 2-6 of these units.
Cavalry(javelin[Socii Equites] or otherwise[Equites]) go in front of the flank troops, or to the side of them. (C-Lancer or C-Jav on Graph.) 2-4 units of this type.
General(s) stay behind the big line. (G on graph.)
Here's a homemade graph to illustrate what I do:
S S S S S S
C-Lancer C-Jav F-H F-T L-I L-I L-I L-I L-I L-I L-I L-I L-I L-I F-H F-T C-Lancer C-Jav
(G) G (G)
That's what my army usually looks like.
As for tactics, if the enemy won't come to me, I use my ranged troops to provoke such
If or when they do get close, the skirmishers pull back, and the main line throws pila, if possible.
Then, the flank troops(Hoplites, Triarii, cavalry) engage the enemy flank troops, and the main
If or when the flank troops win, they go around the melee, and start charging the enemie's
behinds, if possible.
That usually turns into a rout-fest.