A lot of the advice above is very good so some of this repetitive:
1. Study your roster so you will know what you have and don't have. Where you need to upgrade, etc...
2. Do not go crazy during free agency. You may want to avoid all players over 90 in free agency, they cost too much. Look for bargains in free agency, 80+ types with modest salary requirements.
3. Have a draft strategy. Trade down if you are not sure about a pick. Keep an eye on the overall list during the draft so he can see how the draft is going and what players are likely to be taken next.
4. Avoid big contracts and big bonuses unless you are absolutely sure you want that player locked up.
5. After the draft when you get to pick 5 undrafted players look for the sleepers there may be one still there.
6. HERE IS A BIG TIP! Warning: Might be considered something of a spoiler.
7. Make sure your playbook and your philosphies match up.
8. Strip your playbook down (OFF and DEF) to the bare basics and get the plays learned. Then you can add to it. A big playbook is useless if your team doesn't know the plays.
9. And get a decent trainer to help with fatique and injuries.
jw