Continuing to reflect on whether or not you should do your trial client's own appeal, there's something extra to think about if you want to complain about evidence's being excluded at trial. Most of the time, if that's the kind of error you want to bring forward, an offer of proof must be in the record.
Here's the situation: trial counsel offers some evidence; the opponent objects and is sustained by the judge. Generally, if the first lawyer wants to complain on appeal about the exclusion, that lawyer must, outside the presence of the jury, put what the testimony would be on the record. Usually this is done by simply asking the questions and taking the testimony as if the objection had not been made. If the objected-to evidence is simple, the testimony may be offered, if the trial judge allows it, as a narrative, though this is disfavored. After the evidence is presented in the offer of proof, opposing counsel may withdraw the objection or the trial judge might change the ruling sustaining the objection. The offer doesn't have to made right away, but it does have to be made before the case is submitted to the fact-finder.
Evidence exclusion is not a very strong objection, because the standard of review is whether the ruling is in the sound discretion of the court. We'll talk about this more in subsequent posts.