An attorney is a good option - court appointed or retained. The best specific line of defense is going to depend upon the facts and evidence in the particular case and should only be discussed confidentially with that attorney. If you can't afford an attorney, contact the court and ask them how you go about getting a court appointed one.
Often times, even if there is not much of a defense, these types of charges can be settled outside of court with some community service or restitution. Those civil compromises keep there from being a sentence and keep the defendant from getting a criminal record. Ask the attorney about that possibility. Best of luck to you!
There usually isn't much of a choice between a Court appointed attorney and a privately retained attorney. If you can afford an attorney, the Court won't appoint one for you, and if you can't afford one, a Court appointed lawyer is your only option. Either way, you do not want to take this on by yourself, especially with the felony charges pending. Most of the attorneys I know who do Court appointed work are dedicated and skilled lawyers who are swamped with cases. The biggest complaint I hear from people about their public defenders is that their lawyer never spent any time with them. Unfortunately, that is a consequence of having a hundred cases going on at any given time.
Another reason for getting a lawyer is that if you have any desire to resolve this case civilly (which would mean that the Court would dismiss your criminal charge), only your lawyer can negotiate the compromise with the victim (you likely have a no-contact order in place, and even if you didn't you could be accused of Witness Tampering if you contacted them yourself).
Your lawyer can review the specific charges with you and compare your criminal history and show you your best and worst-case scenarios. Even if you aren't sure if you can hire a lawyer, you might want to call around and speak with some private attorneys. My office will speak with you privately over the phone free of charge.
You should get an attorney as soon as you can. Although graffiti or vandalism don't sound like much, Criminal Mischief in the First Degree (which is what it sounds like you described) does fall under the sentencing rules of ORS 137.717, otherwise known as the "Repeat Property Offender" law. Several years ago, this statute was modified by the voters under Ballot Measure 57 and the penalties were greatly enhanced and the judge's ability to provide a lenient sentence was restricted. Thus, prosecutors can, and do, seek prison sentences for such cases. If convicted, probation for someone with no priors is a common outcome.
As others have remarked, a civil compromise is possible with these particular types of charges, which can often get quite expensive. Based on your question ("targets of grafitti"), I am inferring that the graffiti was placed on some kind of public utility or RailRoad property. Those entities can be very expensive to compromise with. However, such an outcome would allow the case to be dismissed in its entirety.
The person who has been charged needs to ask, What will be in jeopardy if I am convicted?
A felony case can put the person who has been charged at risk of: jail, or even prison, depending on the facts of the case; probation, or some other type of supervision; a conviction and record that will negatively affect their future employment opportunities.
Beyond that, it would be difficult to give you a specific answer. Just like a doctor, a lawyer cannot provide reliable legal advise without going through the process of reviewing a specific case with a specific client. While there are some great public defenders out there, I would say that the person should do whatever they can to hire an attorney if at all possible. An attorney who is paid for their services will have an incentive to really know your case inside and out, and give the person the personal attention necessary to do everything possible to beat the charges. Good luck.
***This is NOT legal advice, please consult an attorney for an answer tailored to your situation.***