I recently restarted my Nord warrior build and I'm going about it a lot smarter this time. The first time around I had a hard time justifying level up non-combat skills, but I want to incorporate speech and enchanting this time. Given what I've learned from the game through playing it (once I hit level 30, I was rarely in trouble) would level 20 or so be a good time to start leveling up non-combat skills and selecting perks?

I tend to put perks into even non-combat skills as they naturally lvl, depending on IF I actually want to put perks into it. Speech I have only ever put perks into with one character and he was a "pack peddler" play through. Just for example smithing is generally the 1st thing I put any perks into, IF the character is going to smith. The second point might not come until he/she needs "better" armor... meaning when I notice that the npc's have the next tier up of armor. They may still stay in that Iron armor, but I will put a point into the next lvl up generally Eleven, so I can get to Advanced Armors... then the next point might be used for Arcane smith, specially with an enchanter.

Alchemy ...I will put a point in as soon as my "combat" skills all have at least a single perk point. Enchanting...well that I sometimes wait until I have all the things I need to do a good session of enchanting. But I will "save" a perk when I know I am getting close to that point, even if I am in the middle of a dungeon when I get it. I'll lvl up of course, just not use the perk point. 1/2 the time when I do a session of enchanting the character will lvl up and i'll use that point for one of the combat skills that need's a point.

A lot's going to depend on your build, and what you consider a non-combat and secondary skill. I've always had a hard time finding points for crafting and others with mages, but I've always used the magic reduction skills. Those could be considered non combat, and the question then becomes how many noncombat skills can you afford with a build.