Trading picks is a weird balancing act because there are multiple moving parts and there's always an element of the unknown at play. So, let's cover off some fundamentals:

1. Picks in the approaching draft are more valuable than next seasons.
R1 this season is much more valuable than R1 next season. Why? Because you have more concrete information. As the draft gets closer, the value of your picks increase. Why is this? Because buyers become more eager to make a purchase. If you have the 1st overall pick in the draft it is worth multiple R1 picks in the future. This price is always dictated by the quality of the draft class, and the urgency with which your buyer needs that pick. Would 3 R1s for a single R1 be a good trade? Quite possibly. Depends on the draft class.

2. Evaluate your trading partner
If you're selling picks to a team for their picks in a later season, how much do you think those picks will be worth? How many wins do you think they'll get? Will they make the playoffs? The bowl? Finish dead last? If you're trading for several seasons from now, the guesswork increases. But a straight "your R1 in this draft for their R1 in the next" swap is rarely wise unless you're trading late in the current draft. Why is this?

3. Uncertainty decreases value
The more you know about what you're buying, the more expensive it is. That's why this season's picks are at a premium - you already know which draft position you'll be in, and you know what the draft class looks like. You know neither piece of information next season. You are having to play some major estimation game for the year after that. You can look at the teams in their division to get an initial read, their schedule and how well you think they'll do, the age of their roster and the likelihood they'll lose key players, but ultimately you're taking a punt. Do you think that Stockholm will be drafting in the top 10 two seasons from now? Pretty unlikely.

4. Different rounds, different values
In round 1, the top 10 picks will almost certainly be starters. Some will be star players. There'll be a scattering of stars throughout every round of the draft, but the closest you come to a guarantee of future quality is at the top end of round 1. Later in round 1 and throughout round 2 you should be thinking, probably going to start but will only be a superstar with some luck at training camp. Round 3, moves into future starters, backups and gambles. Round 4 is the lottery ticket round. Selecting high volatility can happen in any round, obviously, but R4 is the "a boom at TC and you're a starter" last chance. By R5 you're hitting players who have a slim chance of breaking positively. R6 and R7 need a lot of luck (or a mutant-build philosophy) to find much of a career. Training camp has a massive amount of influence over this, but using the above as a guide won't steer you too far wrong. Here's a breakdown of the draft class from 1 season ago:
Round 1: one player is currently a free agent, having lost a massive 32 points over the course of the season
Round 2: two players are on free agency. One was a QB gamble, the other has lost 31 points.
Round 3: eight players do not have a contract.
Round 4: twelve players are unsigned.
Round 5: ten players on free agency.
Round 6: nineteen players with no team.
Round 7: seventeen players unsigned.

Why the inconsistency later on? Typically, in round 4, teams will aim for players with very high volatility. This improves the chances they turn into a quality player, but busts can be career ending. In round 5, the most volatile but have some signs of quality have already gone. This makes for less risky, less good players. Fewer catastrophic busts, fewer career-making booms. Round 6, you're looking for any player who has something you can work with, ideally with some volatility to catch a break at Training Camp. Round 7, the best of what's left.

So, should you trade a pair of round 3s for a round 2? That's for you to decide, but have a good think about whether you'll find any value in doing so. Someone wants to sweeten the pot with a round 7? You'll get a better player from free agency.

5. Players vs picks
Even if you're looking at a very high value pick as an offer it doesn't compare to a 100% known quantity. By which I mean a player who has completed their first training camp. At first TC you will learn whether your player is set to improve or decline over the course of their career, once you know this they have a guaranteed value. With a draft pick there is zero guarantee. Whether you value draft picks more than players is your choice, but draft picks are a gamble, known players are a certainty.

6. Expect to pay more for earlier drafting
What denotes fair value varies from owner to owner. Ultimately, a pick is only worth as much as someone is willing to pay for it. The price of picks changes throughout every season, peaking just before the draft starts, then dropping from the second round onwards. Why the second round? Because owners are now looking at what's left in this draft and deciding that the talent has all gone already, so they'd rather pack up and move to next year in the hope that what they need will be there. Hint: every draft class is as bad as every other class, the only thing that changes is the number of better players in each position.

7. If in doubt, get a second opinion
As with all trades, if you're uncertain of whether it's a good idea or not, ask the collective. You'll get a variety of responses, but you'll know pretty fast whether you are over or undervaluing your side of the deal.