Information, as they say, is power

[MysticMonkey]

I am starting a campaign (as a player) and i would like to eventually turn my halfling rogue into a spy master/conman of a sorts.

Any advice on the roll playing aspect? This is a rather vague question I understand.

[LibraryOgre]

Especially due to what may be a typo.

"Roll playing" is slang for "mechanics behind the character"; somewhat pejorative in use, but really going to need to be addressed on a specific system board. If you've got a Pathfinder or 5e question about making the most mechanically effective spymaster, ask there.

"Role playing" addresses the actions and mannerisms you should take... not mechanical things, but "what should I have my character do, for which we will figure out mechanics later."

Assuming you mean the second... be a gossip. Talk to people, buy people drinks, ask them questions, tell them useful pieces of information in trade. You don't give everything away, of course, but your role (until you have a place to do the spymastering) is to gather large quantities of data and take a big picture look at it. Make connections, make friends, and always give away a little bit less than you take in. Did the druid you helped get a silver sickle mention that he was preparing for a heavy winter? Drop that tidbit in a wool merchant's ear and watch him light up. Be willing to pay for information, but also cut off bad sources. Give money to beggars and ask them questions; be every servant's friend with small gifts and loans when they need it, to make sure they share with you general gossip.

[Khedrac]

Mark has covered most of it, but there is one thing I would add: take notes.

And I mean literally try to record everything your character finds out and then, probably between sessions, check it and cross-reference stuff. This will probably give you the odd question to ask the DM at the next session (but make it clear you don't necessarily need an answer there and then).

If you cannot do this without interrupting the flow of play (while you stop to take notes) you probably cannot pull off a spymaster - I know I couldn't, but I have a player who almost certainly can.
It is always worth discussing your intentions with the DM - they may be horrified by the idea (as it does mean more work for them) or they may actively think of obscure references they can drop for you to piece together (or be mislead by).
With the DM's support, and quite a bit of effort, this could be awesome - and it can really please other players who don't really care for trying to keep track of all the information, as they don't need to since you have it covered.

[Maglubiyet]

In addition to chatting up the common folk, make yourself useful to the power brokers - guild masters, wealthy merchants, nobles, crime lords, etc. Orchestrate situations that will put you in close proximity to them. Be the courier that delivers the message, the tailor's assistant while they're getting fitted for a new suit, the coachman who drives them to the banquet.

And while you're doing these things, use the opportunity to give them something they find of value. Information about a rival, this year's latest fashion trend, a new tariff in a neighboring kingdom. Use the information you gain at the street level for this.

[JeenLeen]

Mark has covered most of it, but there is one thing I would add: take notes.

And I mean literally try to record everything your character finds out and then, probably between sessions, check it and cross-reference stuff. This will probably give you the odd question to ask the DM at the next session (but make it clear you don't necessarily need an answer there and then).

If you cannot do this without interrupting the flow of play (while you stop to take notes) you probably cannot pull off a spymaster - I know I couldn't, but I have a player who almost certainly can.
It is always worth discussing your intentions with the DM - they may be horrified by the idea (as it does mean more work for them) or they may actively think of obscure references they can drop for you to piece together (or be mislead by).
With the DM's support, and quite a bit of effort, this could be awesome - and it can really please other players who don't really care for trying to keep track of all the information, as they don't need to since you have it covered.

I wish to emphasize working this out with the DM. A player who is interested in gaining background information and random tidbits (even if useful to the main plot) can be draining on a DM's time and energy, and it can annoy other players. It can be awesome, but work out with your DM ahead-of-time your intentions and what this means. Make sure this spymaster character fits into the game and group playstyle.

I do like your idea. I would possibly enjoy playing such a character. But I know from experience (having annoyed one DM when being a lore collector, and being annoyed as a DM when another player played a lore collector and rumor monger) that it can be draining if not done well.

On a mechanical perspective, talk to your DM about how social skills and 'combat' (if applicable) works. The rules-as-written for such are often poor (and not just in D&D), so houserules and personal interpretations are common. You should be on the same page if you are building your character mechanically to be good at things, lest you put points into things you cannot actually use.

EDIT: An additional thought. Depending on what the DM is willing to do, it might be better to abstract your info and connections. Rather than knowing about an upcoming cold winter from druid A, and knowing you can leak that to the weaver's guild... well, I can't think of a good abstraction without knowing the system, but something like 'Contact Points' you can spend to gain info relevant to the cause or to get leverage over someone involved with the plot. Unless the DM is cool with thinking up the small details and small contacts (and you are cool with maintaining all that), in which case, awesome.

[MysticMonkey]

Usefuls tips thanks! Some of this I had thought of, some not.

My character background, submitted to the DM before we started was that, I am a barber by profession (rogue class) and have a knack for language. Tend to gravitate to people instead of being alone and always like to find out new things and reach into as many social classes as i can applying my trade. Playing 3.5, I went all out with gather information, knowledge local, sense motive and listen. So he is aware at least but maybe not prepared for me needy in that regard.

We have not yet talked about long term character goals yet. But we did at least talk about how I wanted to use my profession to get the info.