Soldier character build question.

A free point will come when you unlock a new level in either Charm or Intimidate. You unlock those levels by selecting conversation lines that happen to award either paragon or renegade points.

You can read ahead which dialogue selections will award paragon or renegade points by consulting the Mass Effect Morality Guide here:

masseffect.wikia.com/wiki/Morality_Guide

At the bottom is a table that shows at what percentages of the paragon and renegade bars charm and intimidate levels will unlock (although there are some errors in this table for some of the later unlocks, mostly due to differences between the PC and Xbox versions).  Also, the BDtS DLC does not appear to affect the ratios as shown in the table.

So, for example, whenever you accumulate 32.4 charm or 32.4 intimidate points, your first additional charm or intimidate slots will open up and the game will place 1 free point in either charm or intimidate, depending on what one is being unlocked.

For the guide, capri233 is using a scenario where you will assign, over the course of the game 6 of your XP points to intimidate and rely on the game to award you 4 free intimidate points over the course of the game. Therefore, the player is assumed to accumulate at least 255.0 renegade points through their dialogue selections.

Of course, when exactly any individual player will reach a "free point" level depends on what dialogue selections they actually make. You will also notice that players start out with different paragon and renegade points based on which background story they select for their Shepard. For example, a Spacer Hero Shepard will start out with 20 paragon points; whereas an Earthborn Ruthless Shepard will start out with 20 renegade points

Personally, I find the combat at the start of the game quite easy, so I tend to assign my first 3 XP points to Intimidate and then use the Intimidate dialogue options throughout the Eden Prime mission.  This does make my Shepard a little "combat weaker" at the start, but being able to use the intimidate dialogue options during Eden Prime does gain Shepard both the Stinger pistol from Cole (the farmers) and the High Explosive Grenade mod from Powell.

Why intimidate rather than charm?  You can focus on acquiring charm points, but the requirements for charm dialogue options near the end of the game are a little higher, so you will need to put in 8 XP points into charm to use those charm dialogue options rather than just 6 XP points to intimidate at those same points in the game.

There are 2 quests that open up in relation to each morality direction.  It is possible to open both quests by carefully splitting the paragon and renegade options, but usually a player will only unlock one or the other.  If a player is OK with glitching, there are a couple of places in the game where dialogues can be repeated a few times to build up an extra amount of either paragon or renegade points.  I believe those are noted in the morality guide.

Other than opening up those quests, a player will get the same amount of opportunities out of the game by role=playing it either as a paragon or a renegade.  A renegade will generally wind up killing a few more of the NPCs throughout the game, although it is also possible to play quite renegade and still save everyone who can possibly be saved.  Brace yourself though - you'll probably wind up replaying the game a few times anyways... at least once as a paragon, once as a renegade, and once as a more mixed character.  It gets to be quite addictive.

Probably way late to this party, but seems to be taken care of.

I would chose one or the other persuade, although I had some characters way back in the day that had a lot of investment in both. Soldier is probably the class you can get away with this the simplest on since you can skip a bonus talent outright, and skip both sniper rifles and shotguns potentially (or at least delay them).