Don't be in such a hurry! You inherit a team with an existing staff with most FA re-signings already done. You may have some RFA's. You will be given a chance to tender those. There is a small problem with the RFA process. If your RFA isn't one of the desirable FAs he may never come up for bids (about 120 or so FAs come up for bidding). If he isn't bid on, he'll just drop through to the open FA market. But if he's not one of the top 120 FAs he's not much of a loss.
You will also have a chance to Franchise Tag one of your unsigned FAs. probably not an attractive option. I'm in season 7 and I've Franchised one player, hoping to move him for a #1 draft pick. Didn't work out and I have a $10M WR for 2014.
Now you get to start building your team. If you sim through this part your GM will probably make decisions you don't like. You can help this a bit by going to the clipboard, Team, Philosophy and setting some limits on what he might do if you elect to sim. There are many other choices related to talent evaluation, roster composition and subbing tired or hurt players.
You can preview the FAs available on the League section of the clipboard. Depending on how many high draft picks you have, you need to reserve $2M to $8M for signing draft picks and hiring walk-ons for training camp. You also need to reserve cap space for renegotiating contracts in season. You can go to your roster, sort by contract years left and identify the players with one year left that you definitely want to resign for future years. Estimate what that will cost and add it to your planned reserve. (Ebongreen's huge tread contains a good article for that). You have to wait for them to come to you during the season.
Now you know about how much you can spend on FAs. The best FAs will come up first. If you win the bidding for total contract value and length, you still have to negotiate the bonus and incentive with the player. The bonus doesn't change the total value of the contract but the incentives do. If you fail to agree on bonus and incentives the FA will go to the second highest bidder but your cap won't be impacted.
RFAs also come up during this process. Be sure to notice what draft picks you have to give up if you sign a RFA. It's not always bad, particularly if you can get a quality, young player giving up only a low round pick, and money, of course.
You want to keep an eye on next year's cap number as well. You can destroy your cap for next year with too many incentives or by cutting or trading players who have bonuses amortized over the length of their contracts.
At some point the trade option will appear on your Clipboard, Roster section. The Free Agent option also is available here during portions of the year. Once the trade option appears, go to trade-away and identify any players you would be willing to trade if the right offer is made. Other teams will then come to you with trade offers and may include those players in packages they want when you go to them to attempt to trade for a player.
If you sim through any significant part of the draft, your GM may trade picks or players to move up or down. You may not like the results.
During the draft you have to start by clicking on the player the GM recommends. Then you will be given the option to take him or not. If not, you can entertain offers to trade down or you can select a player.
The later rounds are a crap shoot until your GM develops the skill that gives you a "similar to" for other NFL players. Then it's an educated crap shoot.
Once the draft is over you almost immediately get the chance to bid on UDFAs. You can give rookie, one year contracts to 5 of those. If they don't make the team, the contract doesn't matter.
One week before the draft the GMs will invite unsigned free agents to camp. You can preempt the other GMs but I don't. I have enough advantages over the CPU without this "feature".
Now you need to sign your draftees. Don't worry too much, they can't go anywhere. The worst thing that ever happened to me was a rookie missing part of training camp. You'll want to make the cuts yourself and probably should select the gameplan for each practice. I played the preseason games the first year to get the hang of playcalling, challenges, timeouts, etc. After the first year you can sim the preseason games.
After the final cut, you may find some attractive FAs that will help your team. I've gotten a few starters and a couple of future pro-bowlers this way.
As the season proceeds, you should see improvement as your players increase play knowledge and your coaches improve their skills. If you have more than a few Missed Assignments at the end of a game, you're not there yet.
You get your first opportunity to hire and fire coaches once your season is over. It's very chaotic. You have almost no information about the coaches or how they will fit your needs. The best coaches who are done with their seasons come up first. The bids are in the power granted the coach, not money. You probably should save as soon as your season is over and go through the staff hiring a couple of times to get the feel of it.
If this sounds like too much planning and management, you may have picked the wrong game. At least for me, that's what it's all about.
Good Luck.