All right... this coming weekend, I'll try to post a "streamlined" (or rather, fully explained) version of AToW character creation. It may be a lot of bookkeeping (which spreadsheets vastly simplify), but it's really not that hard. Really.
OK, here goes...
First, before doing any math, get an idea of the kind of character you want. This should suggest age, Affiliation, and at least the kind of Higher Education (Stage 3) you should be looking at. The Stage 3 you're considering will likely drive some choices for Stages 1 and 2 (e.g., the pre-requisites for Military Academy). Age will suggest how many and what kinds of Stage 4 modules you take. Try to avoid repeating Stage 4 modules other than those that don't grant Attributes (e.g., Civilian Job).
Second, do a first approximation by simply adding up the top line costs of the modules you're considering. You should compare this to 5,000 (or whatever your GM gives you) plus 100 XP per year over 21 if you're IS, or 18 if you're clan (or -100 XP per year under). Add any particularly expensive Traits you want to take (say, 800 XP for that Assault 'mech). If the two numbers are within about 1,000 XP of each other, your concept is probably doable, though you may need to take some negative traits to balance things out.
Now you come to the bookkeeping. There are several spreadsheets posted on the boards here that can help with this (not just mine). BiggRigg42 has also done a few YouTube videos on the process. If you insist on doing it by hand, the best way to keep track of things is to group them by Attributes, Traits and Skills per module.
Rules of thumb:
1) Shoot for minimum Attributes of 4 (except EDG). This is "average", and also the minimum score that won't inflict skill penalties.
2) If you have a minimum requirement above 4, consider taking an Attribute to 7 (where you get a +1 to related skills).
3) As others have noted, Fast Learner will pay for itself if you invest in enough skills. Similarly, if you have few enough skills, and don't plan to play long term, Slow Learner may be worth it.
4) Don't forget the aging effects on Attributes on page 333.
5) Also don't forget that you must purchase 20 XP in an Affiliation Primary or Secondary Language, 20 XP in Language/English, and 10 XP in Perception (per page 52, under Universal Fixed Experience Points; this section also ensures you have at least 100 XP in each Attribute).
6) The Skill Field/Rebate rules are on pages 70-71. The gist of these is that you pay 30 XP to get 30 XP in each skill listed in the field (Fields are chosen from the options presented in the Master Schools List on pages 72-73; the Master Fields List is on pages 82-85), and THEN get 6 XP per skill back as Flexible XP to spend during optimization. Basically, you're only paying 24 XP per skill for 30 XP in those skills.
7) If optimizing without a spreadsheet, the table on page 85 is your guide for skills. Attributes and Traits mostly cost XP evenly divisible by 100, so optimizing those should be even simpler.
8) Optimization is simply the harvesting of "excess" points that don't get you to the next level of Attribute, Trait or Skill, and you can spend them anyway you like.
9) Remember that negative Traits acquired via Life Modules don't count toward the maximum 10% of starting XP limit on negative Traits. The limit only applies to negative Traits you take above and beyond those. This is one of the reasons the "first approximation" works.
10) Don't forget Attribute minimums and pre-requisites for Modules or Skill Fields.
