Where I put skills/stats really depends on the game.
FO2
PE determines many things such as ranged damage modifers, sequence, and initial distance during random encounters; minimum of 6 is good enough for Better Criticals perk, though it can go a little higher for a gun-toting character. IN governs skill points and opens dialogue options; playing as a retard (IN<4 if I recall correctly) blocks many quests opportunities. AG should be maxed so you can take advantage of every turn in battle. For every 2 levels of CH, an additional companion can be added to your party; something that is very helpful when you are carrying extra items or need help against overwhelming numbers.
Repair seems negligible when weapons and armor don't deteriorate like FO3 and FO:NV; recruiting Vic can cover situations that require it. Any weapon skills you specialize in can have benefits when raised past 100%. Steal doesn't seem to be as useful since moving behind an NPC can make up for it.
FO3
In terms of SPECIAL, I put CH down to 1 since the stat doesn't modify anything outside of initial Speech and Barter skill, which can be raised through spending points whenever leveled up. IN is good to have since it can help you raise skills in more areas and get perks that have certain skill requirements early on. PE is not as useful as the other games before it, it's best kept at 4 and raised to 6 via Perception bobblehead and Ant Perception perk to acquire the Better Criticals perk. I like EN to be at least 5 to acquire Toughness perk. Everything else depends on the weapon(s) I'm planning to use the most.
When it comes to combat skills, I only invest one type...though with a combination of high in INT, educated perk, and skill books, it's possible to max out a second one. Explosives can be fun, but I find it the most difficult to use effectively on its own. For non-combat skills, Lockpick and Science are the most preferred. Speech is left alone until the non-combat other skills are maxed up.
FO:NV
I follow a similar set up to FO3, with more things to consider. ST is now a requirement for certain weapons (just like the classic games), and they are adjusted according to weapon I want to use towards the end of the game. A high enough PE can open some dialogue options. A LK of 7 minimum is required to put gambling in your favor. INT is still useful, but not strong as it was in FO3. CH holds more weight this time around since it can make followers stronger, but I just keep it at 1 since I mainly use them as pack mules than protection.
In NV, Barter has uses in speech checks as well as trading, so there is a greater incentive to raise it up. Speech checks need to be raised since they are now based on passing a minimum Speech skill rather than percentages.